Practice nursing care for clients with Diabetes Mellitus II

 

Diabetes mellitus is a group of metabolic diseases characterized by elevated levels of glucose in the blood (hyperglycemia) resulting from defects in insulin secretion, insulin action, or both (American Diabetes Association [ADA], Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003). Normally a certain amount of glucose circulates in the blood. The major sources of this glucose are absorption of ingested food in the gastrointestinal (GI) tract and formation of glucose by the liver from food substances.

Insulin, a hormone produced by the pancreas, controls the level of glucose in the blood by regulating the production and storage of glucose. In the diabetic state, the cells may stop responding to insulin or the pancreas may stop producing insulin entirely. This leads to hyperglycemia, which may result in acute metabolic complications such as diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar nonketotic syndrome (HHNS). Long-term effects of hyperglycemia contribute to macrovascular complications (coronary artery disease, cerebrovascular disease, and peripheral vascular disease), chronic microvascular complications (kidney and eye disease), and neuropathic complications (diseases of the nerves). Diabetes mellitus affects about 17 million people, 5.9 million of whom are undiagnosed. In the United States, approximately 800,000 new cases of diabetes are diagnosed yearly (Mokdad et al., 2000). Diabetes is especially prevalent in the elderly, with up to 50% of people older than 65 suffering some degree of glucose intolerance. Among adults in the United States, diagnosed cases of diabetes increased 49% from 1990 to 2000, and similar increases are expected to continue (Centers for Disease Control and Prevention [CDC], 2002). Minority groups share a disproportionate burden of diabetes compared to non-minority groups. African-Americans and other racial and ethnic groups (Native Americans and persons of Hispanic origin) are more likely than Caucasians to develop diabetes and are at greater risk for many of the complications and higher death rates due to diabetes than Caucasians (U.S. Public Health Service [USPHS], 2000; CDC, 2002).

 The far-reaching and devastating physical, social, and economic consequences of diabetes are as follows:

In the United States, diabetes is the leading cause of nontraumatic amputations, blindness among working-age adults, and end-stage renal disease (USPHS, 2000).

Diabetes is the third leading cause of death by disease, primarily because of the high rate of cardiovascular disease (myocardial infarction, stroke, and peripheral vascular disease) among people with diabetes.

Hospitalization rates for people with diabetes are 2.4 times greater for adults and 5.3 times greater for children than for the general population.

The economic cost of diabetes continues to rise because of increasing health care costs and an aging population. Half of all people who have diabetes and who are older than 65 are hospitalized each year, and severe and life-threatening complications often contribute to the increased rates of hospitalization. Costs related to diabetes are estimated to be almost $100 billion annually, including direct medical care expenses and indirect costs attributable to disability and premature death (CDC, 2002). The primary goals of treatment for patients with diabetes include controlling blood glucose levels and preventing acute and long-term complications. Thus, the nurse who cares for diabetic patients must assist them to develop self-care management skills.

 

Classification of Diabetes

 

There are several different types of diabetes mellitus; they may differ in cause, clinical course, and treatment. The major classifications of diabetes are:

Type 1 diabetes (previously referred to as insulin-dependent diabetes mellitus)

Type 2 diabetes (previously referred to as non-insulindependent diabetes mellitus)

Gestational diabetes mellitus (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003)

Diabetes mellitus associated with other conditions or syndromes

OVERVIEW

The terms “insulin-dependent diabetes” and “non-insulindependent diabetes” and their acronyms (IDDM and NIDDM, respectively) are no longer used because they have resulted in classification of patients on the basis of the treatment of their diabetes rather than the underlying etiology. Use of Roman numerals (type I and type II) to distinguish between the two types has been changed to type 1 and type 2 to reduce confusion (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003). Approximately 5% to 10% of people with diabetes have type 1 diabetes, in which the insulin-producing pancreatic beta cells are destroyed by an autoimmune process. As a result, they produce little or no insulin and require insulin injections to control their blood glucose levels. Type 1 diabetes is characterized by an acute onset, usually before age 30 (CDC, Diabetes Surveillance, 1999). Approximately 90% to 95% of people with diabetes have type 2 diabetes (CDC, Data Factsheet, 2002), which results from decreased sensitivity to insulin (called insulin resistance) and impaired beta cell functioning resulting in decreased insulin production (Quinn, 2001a). Type 2 diabetes is first treated with diet and exercise. If elevated glucose levels persist, diet and exercise are supplemented with oral hypoglycemic agents. In some individuals with type 2 diabetes, oral agents do not control hyperglycemia, and insulin injections are required. In addition, some individuals whose type 2 diabetes can usually be controlled with diet, exercise, and oral agents may require insulin injections during periods of acute physiologic stress (eg, illness or surgery). Type 2 diabetes occurs more among people who are older than 30 years and obese (Diabetes Information Clearing House, 2001). Diabetes complications may develop in any person with type 1 or type 2 diabetes, not only in patients who take insulin. Some patients with type 2 diabetes who are treated with oral medications may have the impression that they do not really have diabetes or that they simply have “borderline” diabetes. They may believe that, compared with diabetic patients who require insulin injections, their diabetes is not a serious problem. It is important for the nurse to emphasize to these individuals that they do have diabetes and not a borderline problem with sugar (glucose).

Borderline diabetes is classified as impaired glucose tolerance (IGT) or impaired fasting glucose (IFG) and refers to a condition in which blood glucose levels fall between normal levels and levels considered diagnostic for diabetes. This classification system is dynamic in two ways. First, research findings suggest many differences among individuals within each category. Second, except for those with type 1 diabetes, patients may move from one category to another. For example, a woman with gestational diabetes may, after delivery, move into the type 2 category. These types also differ in their etiology, clinical course, and management.

 

PHYSIOLOGY AND PATHOPHYSIOLOGY OF DIABETES

 

Type I Diabetes

 

Insulin is secreted by beta cells, which are one of four types of cells in the islets of Langerhans in the pancreas.

Islets of Langerhans

 

Insulin is an anabolic, or storage, hormone. When a person eats a meal, insulin secretion increases and moves glucose from the blood into muscle, liver, and fat cells.

In those cells, insulin:

Transports and metabolizes glucose for energy

Stimulates storage of glucose in the liver and muscle (in the form of glycogen)

Signals the liver to stop the release of glucose

Enhances storage of dietary fat in adipose tissue

Accelerates transport of amino acids (derived from dietary protein) into cells Insulin also inhibits the breakdown of stored glucose, protein, and fat.

During fasting periods (between meals and overnight), the pancreas continuously releases a small amount of insulin (basal insulin); another pancreatic hormone called glucagon (secreted by the alpha cells of the islets of Langerhans) is released when blood glucose levels decrease and stimulate the liver to release stored glucose. The insulin and the glucagon together maintain a constant level of glucose in the blood by stimulating the release of glucose from the liver. Initially, the liver produces glucose through the breakdown of glycogen (glycogenolysis). After 8 to 12 hours without food, the liver forms glucose from the breakdown of noncarbohydrate substances, including amino acids (gluconeogenesis).

 

TYPE 1 DIABETES

 

Type 1 diabetes is characterized by destruction of the pancreatic beta cells. It is thought that combined genetic, immunologic, and possibly environmental (eg, viral) factors contribute to beta cell destruction. Although the events that lead to beta cell destruction are not fully understood, it is generally accepted that a genetic susceptibility is a common underlying factor in the development of type 1 diabetes. People do not inherit type 1 diabetes itself; rather, they inherit a genetic predisposition, or tendency, toward developing type 1 diabetes. This genetic tendency has been found in people with certain HLA (human leukocyte antigen) types. HLA refers to a cluster of genes responsible for transplantation antigens and other immune processes. About 95% of Caucasians with type 1 diabetes exhibit specific HLA types (DR3 or DR4). The risk of developing type 1 diabetes is increased three to five times in people who have one of these two HLA types. The risk increases 10 to 20 times in people who have both DR3 and DR4 HLA types (as compared with the general population). Immune-mediated diabetes commonly develops during childhood and adolescence, but it can occur at any age (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003). There is also evidence of an autoimmune response in type 1 diabetes. This is an abnormal response in which antibodies are directed against normal tissues of the body, responding to these tissues as if they are foreign.

Autoantibodies against islet cells and against endogenous (internal) insulin have been detected in people at the time of diagnosis and even several years before the development of clinical signs of type 1 diabetes. In addition to genetic and immunologic components, environmental factors, such as viruses or toxins, that may initiate destruction of the beta cell are being investigated. Regardless of the specific etiology, the destruction of the beta cells results in decreased insulin production, unchecked glucose production by the liver, and fasting hyperglycemia. In addition, glucose derived from food cannot be stored in the liver but instead remains in the bloodstream and contributes to postprandial (after meals) hyperglycemia. If the concentration of glucose in the blood exceeds the renal threshold for glucose, usually 180 to 200 mg/dL (9.9 to 11.1 mmol/L), the kidneys may not reabsorb all of the filtered glucose; the glucose then appears in the urine (glucosuria). When excess glucose is excreted in the urine, it is accompanied by excessive loss of fluids and electrolytes. This is called osmotic diuresis. Because insulin normally inhibits glycogenolysis (breakdown of stored glucose) and gluconeogenesis (production of new glucose from amino acids and other substrates), in people with insulin deficiency, these processes occur in an unrestrained fashion and contribute further to hyperglycemia. In addition, fat breakdown occurs, resulting in an increased production of ketone bodies, which are the byproducts of fat breakdown.

 

TYPE 2 DIABETES

The two main problems related to insulin in type 2 diabetes are insulin resistance and impaired insulin secretion. Insulin resistance refers to a decreased tissue sensitivity to insulin. Normally, insulin binds to special receptors on cell surfaces and initiates a series of reactions involved in glucose metabolism. In type 2 diabetes, these intracellular reactions are diminished, thus rendering insulin less effective at stimulating glucose uptake by the tissues and at regulating glucose release by the liver (Fig. 41-1). The exact mechanisms that lead to insulin resistance and impaired insulin secretion in type 2 diabetes are unknown, although genetic factors are thought to play a role. To overcome insulin resistance and to prevent the buildup of glucose in the blood, increased amounts of insulin must be secreted to maintain the glucose level at a normal or slightly elevated level. However, if the beta cells cannot keep up with the increased demand for insulin, the glucose level rises, and type 2 diabetes develops. Despite the impaired insulin secretion that is characteristic of type 2 diabetes, there is enough insulin present to prevent the breakdown of fat and the accompanying production of ketone bodies. Therefore, DKA does not typically occur in type 2 diabetes. Uncontrolled type 2 diabetes may, however, lead to another acute problem, HHNS (see later discussion).

Type 2 diabetes occurs most commonly in people older than 30 years who are obese, although its incidence is increasing in younger adults (CDC, Diabetes Surveillance, 2002). Because it is associated with a slow (over years), progressive glucose intolerance, the onset of type 2 diabetes may go undetected for many years. If symptoms are experienced, they are frequently mild and may include fatigue, irritability, polyuria, polydipsia, skin wounds that heal poorly, vaginal infections, or blurred vision (if glucose levels are very high).

 For most patients (approximately 75%), type 2 diabetes is detected incidentally (eg, when routine laboratory tests or ophthalmoscopic examinations are performed). One consequence of undetected diabetes is that long-term diabetes complications (eg, eye disease, peripheral neuropathy, peripheral vascular disease) may have developed before the actual diagnosis of diabetes is made (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003). Because insulin resistance is associated with obesity, the primary treatment of type 2 diabetes is weight loss. Exercise is also important in enhancing the effectiveness of insulin. Oral antidiabetic agents may be added if diet and exercise are not successful in controlling blood glucose levels. If maximum doses of a single category of oral agents fail to reduce glucose levels to satisfactory levels, additional oral agents may be used. Insulin may be added to oral agent therapy, or patients may move to insulin therapy entirely. Some patients require insulin on an ongoing basis, and others may require insulin on a temporary basis during periods of acute physiologic stress, such as illness or surgery. A recent report has demonstrated that type 2 diabetes can be prevented or delayed in persons at high risk for the disease through weight reduction and increased participation in moderate exercise (Diabetes Prevention Program Research Group, 2002). Metformin, one of the antidiabetic agents, also prevented or delayed the onset of type 2 diabetes, but to a lesser degree.

GESTATIONAL DIABETES

Gestational diabetes is any degree of glucose intolerance with its onset during pregnancy. Hyperglycemia develops during pregnancy because of the secretion of placental hormones, which causes insulin resistance. For women who meet one or more of the following criteria, selective screening for diabetes during pregnancy is now being recommended between the 24th and 28th weeks of gestation: age 25 years or older; age 25 years or younger and obese; family history of diabetes in first-degree relatives; or member of an ethnic/racial group with a high prevalence of diabetes (eg, Hispanic American, Native American, Asian American, African American, or Pacific Islander). Gestational diabetes occurs in up to 14% of pregnant women and increases their risk for hypertensive disorders during pregnancy (ADA, Gestational Diabetes Mellitus, 2003). Initial management includes dietary modification and blood glucose monitoring. If hyperglycemia persists, insulin is prescribed. Oral antidiabetic agents should not be used during pregnancy. Goals for blood glucose levels during pregnancy are 105 mg/dL (5.8 mmol/L) or less before meals and 120 mg/dL (6.7 mmol/L) or less 2 hours after meals (ADA, Gestational Diabetes Mellitus, 2003). After delivery of the infant, blood glucose levels in the woman with gestational diabetes return to normal. However, many women who have had gestational diabetes develop type 2 diabetes later in life. Therefore, all women who have had gestational diabetes should be counseled to maintain their ideal body weight and to exercise regularly to reduce their risk for type 2 diabetes (ADA, Gestational Diabetes Mellitus, 2003).

 

CLINICAL MANIFESTATIONS

 

 

Clinical manifestations of all types of diabetes include the “three Ps”: polyuria, polydipsia, and polyphagia.

Polyuria (increased urination) and polydipsia (increased thirst) occur as a result of the excess loss of fluid associated with osmotic diuresis.

The patient also experiences polyphagia (increased appetite) resulting from the catabolic state induced by insulin deficiency and the breakdown of proteins and fats. Other symptoms include fatigue and weakness, sudden vision changes, tingling or numbness in hands or feet, dry skin, skin lesions or wounds that are slow to heal, and recurrent infections. The onset of type 1 diabetes may also be associated with sudden weight loss or nausea, vomiting, or abdominal pains, if DKA has developed.

ASSESSMENT AND DIAGNOSTIC FINDINGS

An abnormally high blood glucose level is the basic criterion for the diabetes diagnosis.

Fasting plasma glucose (FPG) levels of 126 mg/dL (7.0 mmol/L) or more or random plasma glucose levels exceeding 200 mg/dL (11.1 mmol/L) on more than one occasion are diagnostic of diabetes. The oral glucose tolerance test and the intravenous glucose tolerance test are no longer recommended for routine clinical use. See Chart 41-3 for the ADA’s diagnostic criteria for diabetes mellitus (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003). Plasma glucose values may be 10% to 15% higher than whole blood values, which are obtained with finger sticks (Porth, 2002). In addition to the assessment and diagnostic evaluation performed to diagnose diabetes, ongoing specialized assessment of patients with known diabetes and evaluation for complications in patients with newly diagnosed diabetes are important components of care.

Blood Test

 

Glucose Test

 

 

Gerontologic Considerations

Elevated blood glucose levels appear to be age-related and occur in both men and women throughout the world. Elevated blood glucose levels commonly appear in the fifth decade of life and increase in frequency with advancing age. When elderly people with overt diabetes are excluded from the statistics, approximately 10% to 30% of elderly people have age-related hyperglycemia. What causes age-related changes in carbohydrate metabolism is unresolved. Possibilities include poor diet, physical inactivity, a decrease in the lean body mass in which ingested carbohydrate may be stored, altered insulin secretion, and increase in fat tissue, which increases insulin resistance.

Diabetes Management

The main goal of diabetes treatment is to normalize insulin activity and blood glucose levels to reduce the development of vascular and neuropathic complications. The importance of tight blood glucose control was demonstrated by the Diabetes Control and Complications Trial (DCCT), a 10-year prospective clinical trial conducted from 1983 to 1993. The trial investigated the impact of intensive glucose control on the development and progression of complications such as retinopathy, nephropathy, and neuropathy.

 

Diabetic Retinopathy

 

A cohort of 1,441 people with type 1 diabetes were randomly assigned to conventional treatment (one or two insulin injections per day) or intensive treatment (three or four insulin injections per day or insulin pump therapy plus frequent blood glucose monitoring and weekly contacts with diabetes educators). Results demonstrated that the risk for developing retinopathy, neuropathy, and early signs of nephropathy (microalbuminuria and albuminuria) was dramatically reduced. The reduction was attributed to control of blood glucose levels to normal or nearnormal levels. The ADA now recommends that all patients with diabetes strive for glucose control to reduce their risks for complications (ADA, Implications of the Diabetes Control and Complications Trial, 2003).

The major adverse effect of intensive therapy was a threefold increase in the incidence of severe hypoglycemia (severe enough to require assistance from another person), coma, or seizure. Because of these adverse effects, intensive therapy must be initiated with caution and must be accompanied by thorough education of the patient and family and by responsible behavior of the patient. Careful screening of patients is a key step in initiating intensive therapy. (For situations that preclude the initiation of very tight blood glucose control, see the discussion of insulin in this chapter.) A study conducted in the United Kingdom and reported in 1998 supported the results of the DCCT in type 2 diabetes and demonstrated a decrease in complications in patients with type 2 diabetes receiving intensive therapy compared to those receiving conventional therapy (United Kingdom Prospective Diabetes Study Group [UKPDS], 1998; ADA, Implications of the United Kingdom Prospective Diabetes Study, 2003). Therefore, the therapeutic goal for diabetes management is to achieve normal blood glucose levels (euglycemia) without hypoglycemia and without seriously disrupting the patient’s usual lifestyle and activity.

There are five components of diabetes management:

 Nutritional management

Exercise

Monitoring

Pharmacologic therapy

 Education Treatment varies because of changes in lifestyle and physical and emotional status as well as advances in treatment methods.

Therefore, diabetes management involves constant assessment and modification of the treatment plan by health professionals and daily adjustments in therapy by the patient. Although the health care team directs the treatment, it is the patient who must manage the complex therapeutic regimen. For this reason, patient and family education is an essential component of diabetes treatment and is as important as all other components of the regimen.

 

NUTRITIONAL MANAGEMENT

 

Nutrition, diet, and weight control are the foundation of diabetes management. The most important objective in the dietary and nutritional management of diabetes is control of total caloric intake to attain or maintain a reasonable body weight and control of blood glucose levels. Success of this alone is often associated with reversal of hyperglycemia in type 2 diabetes. However, achieving this goal is not always easy. Because nutritional man- agement of diabetes is so complex, a registered dietitian who understands diabetes management has the major responsibility for this aspect of the therapeutic plan. However, the nurse and all other members of the health care team need to be knowledgeable about nutritional therapy and supportive of the patient who needs to implement dietary and lifestyle changes (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003).

 Nutritional management of the diabetic patient includes the following goals (ADA, Evidence-Based Nutrition Principles and Recommendations for the Treatment and Prevention of Diabetes and Related Complications, 2003):

 Providing all the essential food constituents (eg, vitamins, minerals) necessary for optimal nutrition

 Meeting energy needs

Achieving and maintaining a reasonable weight

 Preventing wide daily fluctuations in blood glucose levels, with blood glucose levels as close to normal as is safe and practical to prevent or reduce the risk for complications

Decreasing serum lipid levels, if elevated, to reduce the risk for macrovascular disease

For patients who require insulin to help control blood glucose levels, maintaining as much consistency as possible in the amount of calories and carbohydrates ingested at different meal times is essential. In addition, consistency in the approximate time intervals between meals, with the addition of snacks if necessary, helps in preventing hypoglycemic reactions and in maintaining overall blood glucose control. For obese diabetic patients (especially those with type 2 diabetes), weight loss is the key to treatment. (It is also a major factor in preventing diabetes.) In general, overweight is considered to be a body mass index (BMI) of 25 to 29; obesity is defined as 20% above ideal body weight or a BMI equal to or greater than 30 (National Institutes of Health, 2000). BMI is a weight-to-height ratio calculated by dividing body weight (in kilograms) by the square of the height (in meters). Calculation of BMI is discussed in Chapter 5.

Obesity is associated with an increased resistance to insulin; it is also a main factor in type 2 diabetes. Some obese patients who have type 2 diabetes and who require insulin or oral agents to control blood glucose levels may be able to reduce or eliminate the need for medication through weight loss. A weight loss as small as 10% of total weight may significantly improve blood glucose levels. For obese diabetic patients who do not take insulin, consistent meal content or timing is not as critical. Rather, decreasing the overall caloric intake assumes more importance. However, meals should not be skipped. Pacing food intake throughout the day places more manageable demands on the pancreas. Long-term adherence to the meal plan is one of the most challenging aspects of diabetes management. For obese patients, it may be more realistic to restrict calories only moderately. For those who have lost weight, maintaining the weight loss may be difficult. To help these patients incorporate new dietary habits into their lifestyles, diet education, behavioral therapy, group support, and ongoing nutrition counseling are encouraged.

Meal Planning and Related Teaching

For all patients with diabetes, the meal plan must consider the patient’s food preferences, lifestyle, usual eating times, and ethnic and cultural background. For patients using intensive insulin therapy, there may be greater flexibility in the timing and content of meals by allowing adjustments in insulin dosage for changes in eating and exercise habits. Advances in insulin management (new insulin analogs, insulin algorithms, insulin pumps) permit greater flexibility of schedules than previously possible. This is in contrast to the older concept of maintaining a constant dose of insulin and requiring the patient to adjust his or her schedule to the actions and duration of the insulin. The first step in preparing a meal plan is a thorough review of the patient’s diet history to identify his or her eating habits and lifestyle. A thorough assessment of the patient’s need for weight loss, gain, or maintenance is also undertaken. In most instances, the person with type 2 diabetes requires weight reduction. In teaching about meal planning, the clinical dietitian uses various educational tools, materials, and approaches. Initial education addresses the importance of consistent eating habits, the relationship of food and insulin, and the provision of an individualized meal plan. In-depth follow-up education then focuses on management skills, such as eating at restaurants, reading food labels, and adjusting the meal plan for exercise, illness, and special occasions. The nurse plays an important role in communicating pertinent information to the dietitian and reinforcing the patient’s understanding. For some patients, certain aspects of meal planning, such as the food exchange system, may be difficult to learn. This may be related to limitations in the patient’s intellectual level or to emotional issues, such as difficulty accepting the diagnosis of diabetes or feelings of deprivation and undue restriction in eating. In any case, it helps to emphasize that using the exchange system (or any food classification system) provides a new way of thinking about food rather than a new way of eating. It is also important to simplify information as much as possible and to provide opportunities for the patient to practice and repeat activities and information.

 

CALORIC REQUIREMENTS

 

Calorie-controlled diets are planned by first calculating the individual’s energy needs and caloric requirements based on the patient’s age, gender, height, and weight. An activity element is then factored in to provide the actual number of calories required for weight maintenance. To promote a 1- to 2-pound weight loss per week, 500 to 1,000 calories are subtracted from the daily total. The calories are distributed into carbohydrates, proteins, and fats, and a meal plan is then developed. The 1995 Exchange Lists for Meal Planning (ADA, 1995) are presented to the patient using the appropriate amount of calories, with strict diet adherence as the goal. Unfortunately, caloriecontrolled diets are often confusing and difficult to comply with. They require patients to measure precise portions and to eat specific foods and amounts at each meal and snack. In this instance, developing a meal plan based on the individual’s usual eating habits and lifestyle may be a more realistic approach to glucose control and weight loss or weight maintenance. In both instances, the patient needs to work closely with a registered dietitian to assess current eating habits and to achieve realistic, individualized goals. The priority for a young patient with type 1 diabetes, for example, should be a diet with enough calories to maintain normal growth and development. Some patients may be underweight at the onset of type 1 diabetes because of rapid weight loss from severe hyperglycemia. The goal with these patients initially may be to provide a higher-calorie diet to regain lost weight.

CALORIC DISTRIBUTION

A diabetic meal plan also focuses on the percentage of calories to come from carbohydrates, proteins, and fats. In general, carbohydrate foods have the greatest effect on blood glucose levels because they are more quickly digested than other foods and are converted into glucose rapidly. Several decades ago it was recommended that diabetic diets contain more calories from protein and fat foods than from carbohydrates to reduce postprandial increases in blood glucose levels. However, this resulted in a dietary intake inconsistent with the goal of reducing the cardiovascular disease commonly associated with diabetes (ADA, Evidence-Based Nutrition Principles and Recommendations for the Treatment and Prevention of Diabetes and Related Complications, 2003).

Carbohydrates.

The caloric distribution currently recommended is higher in carbohydrates than in fat and protein. However, research into the appropriateness of a higher-carbohydrate diet in patients with decreased glucose tolerance is ongoing, and recommendations may change accordingly. Currently, the ADA and the American Dietetic Association recommend that for all levels of caloric intake, 50% to 60% of calories should be derived from carbohydrates, 20% to 30% from fat, and the remaining 10% to 20% from protein. These recommendations are also consistent with those of the American Heart Association, American Cancer Society, and the U.S. Department of Agriculture (2000). Carbohydrates consist of sugars and starches. Little scientific evidence supports the belief that sugars, such as sucrose, promote a greater blood glucose level compared to starches (eg, rice, pasta, or bread). Although low glycemic index diets (described below) may reduce postprandial glucose levels, there seem to be no clear effects on outcomes (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003). Thus, the latest nutrition guidelines recommend that all carbohydrates be eaten in moderation to avoid high postprandial blood glucose levels (ADA, Exchange Lists for Meal Planning, 1995). Foods high in carbohydrates, such as sucrose, are not eliminated from the diet but should be eaten in moderation (up to 10% of total calories) because these foods are typically high in fat and lack vitamins, minerals, and fiber. Carbohydrate counting is another nutritional tool used for blood glucose management because carbohydrates are the main nutrients in food that influence blood glucose levels. This method provides flexibility in food choices, can be less complicated to understand than the diabetic food exchange list, and allows more accurate management with multiple daily injections (insulin before each meal). However, if carbohydrate counting is not used with other meal-planning techniques, weight gain can result. A variety of methods are used to count carbohydrates. When developing a diabetic meal plan using carbohydrate counting, all food sources should be considered. Once digested, 100% of carbohydrates are converted to glucose. However, approximately 50% of protein foods (meat, fish, and poultry) are also converted to glucose. One method of carbohydrate counting includes counting grams of carbohydrates. If target goals are not reached by counting carbohydrates alone, protein will be factored into the calculations. This is especially true if the meal consists of only meat, fish, and non-starchy vegetables. An alternative to counting grams of carbohydrate is measuring servings or choices. This method is used more often by people with type 2 diabetes. It is similar to the food exchange list and emphasizes portion control of total servings of carbohydrate at meals and snacks. One carbohydrate serving is equivalent to 15 g of carbohydrate. Examples of one serving are an apple 2 inches in diameter and one slice of bread. Vegetables and meat are counted as one third of a carbohydrate serving. Although carbohydrate counting is now commonly used for blood glucose management with type 1 and type 2 diabetes, it is not a perfect system. All carbohydrates, to some extent, affect the blood glucose to different degrees, regardless of equivalent serving size.

Fats.

The recommendations regarding fat content of the diabetic diet include both reducing the total percentage of calories from fat sources to less than 30% of the total calories and limiting the amount of saturated fats to 10% of total calories. Additional recommendations include limiting the total intake of dietary cholesterol to less than 300 mg/day. This approach may help to reduce risk factors such as elevated serum cholesterol levels, which are associated with the development of coronary artery disease, the leading cause of death and disability among people with diabetes. The meal plan may include the use of some nonanimal sources of protein (eg, legumes and whole grains) to help reduce saturated fat and cholesterol intake. In addition, the amount of protein intake may be reduced in patients with early signs of renal disease.

Fiber.

The use of fiber in diabetic diets has received increased attention as researchers study the effects on diabetes of a highcarbohydrate, high-fiber diet. This type of diet plays a role in lowering total cholesterol and low-density lipoprotein cholesterol in the blood. Increasing fiber in the diet may also improve blood glucose levels and decrease the need for exogenous insulin. There are two types of dietary fibers: soluble and insoluble. Soluble fiber—in foods such as legumes, oats, and some fruits— plays more of a role in lowering blood glucose and lipid levels than does insoluble fiber, although the clinical significance of this effect is probably small (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003). Soluble fiber is thought to be related to the formation of a gel in the GI tract. This gel slows stomach emptying and the movement of food through the upper digestive tract. The potential glucose-lowering effect of fiber may be caused by the slower rate of glucose absorption from foods that contain soluble fiber. Insoluble fiber is found in whole-grain breads and cereals and in some vegetables. This type of fiber plays more of a role in increasing stool bulk and preventing constipation. Both insoluble and soluble fibers increase satiety, which is helpful for weight loss. One risk involved in suddenly increasing fiber intake is that it may require adjusting the dosage of insulin or oral agents to prevent hypoglycemia. Other problems may include abdominal fullness, nausea, diarrhea, increased flatulence, and constipation if fluid intake is inadequate. If fiber is added to or increased in the meal plan, it should be done gradually and in consultation with a dietitian. The 1995 Exchange Lists for Meal Planning (ADA, 1995) is an excellent guide for increasing fiber intake. Fiber-rich food choices within the vegetable, fruit, and starch/bread exchanges are highlighted in the lists.

FOOD CLASSIFICATION SYSTEMS

To teach diet principles and to help patients in meal planning, several systems have been developed in which foods are organized into groups with common characteristics, such as number of calories, composition of foods (ie, amount of protein, fat, or carbohydrate in the food), or effect on blood glucose levels.

Exchange Lists.

A commonly used tool for nutritional management is the Exchange Lists for Meal Planning (ADA, 1995). There are six main exchange lists: bread/starch, vegetable, milk, meat, fruit, and fat. Foods included on one list (in the amounts specified) contain equal numbers of calories and are approximately equal in grams of protein, fat, and carbohydrate. Meal plans (tailored to the patient’s needs and preferences) are based on a recommended number of choices from each exchange list. Foods on one list may be interchanged with one another, allowing the patient to choose a variety while maintaining as much consistency as possible in the nutrient content of foods eaten. Table 41-2 presents three sample lunch menus that are interchangeable in terms of carbohydrate, protein, and fat content. Exchange list information on combination foods, such as pizza, chili, and casseroles, and convenience foods, desserts, snack foods, and fast foods is available from the ADA. Some food manufacturers and restaurants publish exchange lists that describe their products as well. For more nutrition information, contact the ADA (see address at end of the chapter).

The Food Guide Pyramid.

 

diabet diet

 

The Food Guide Pyramid is another tool used to develop meal plans. It is commonly used for patients with type 2 diabetes who have a difficult time complying with a calorie-controlled diet.

The food pyramid consists of six food groups:

(1) bread, cereal, rice, and pasta;

(2) fruits;

(3) vegetables;

 (4) meat, poultry, fish, dry beans, eggs, and nuts;

(5) milk, yogurt, and cheese;

and (6) fats, oils, and sweets.

The pyramid shape was chosen to emphasize that the foods in the largest area, the base of the pyramid (starches, fruits, and vegetables), are lowest in calories and fat and highest in fiber and should make up the basis of the diet. For those with diabetes, as well as for the general population, 50% to 60% of the daily caloric intake should be from these three groups. As one moves up the pyramid, foods higher in fat (particularly saturated fat) are illustrated; these foods should account for a smaller percentage of the daily caloric intake. The very top of the pyramid comprises fats, oils, and sweets, foods that should be used sparingly by people with diabetes to obtain weight and blood glucose control and to reduce the risk for cardiovascular disease. Reliance on the Food Guide Pyramid, however, may result in fluctuations in blood glucose levels because high-carbohydrate foods may be grouped with low-carbohydrate foods. The pyramid is appropriately used only as a first-step teaching tool (Dixon, Cronin, & Krebs-Smith, 2001) for patients learning how to control food portions and how to identify which foods contain carbohydrate, protein, and fat.

Glycemic Index.

One of the main goals of diet therapy in diabetes is to avoid sharp, rapid increases in blood glucose levels after food is eaten. The term “glycemic index” is used to describe how much a given food raises the blood glucose level compared with an equivalent amount of glucose; however, the effects on blood glucose levels and on long-term patient outcomes have been questioned (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003).

Although more research is necessary, the following guidelines can be helpful when making dietary recommendations:

Combining starchy foods with protein- and fat-containing foods tends to slow their absorption and lower the glycemic response.

In general, eating foods that are raw and whole results in a lower glycemic response than eating chopped, pured, or cooked foods.

 Eating whole fruit instead of drinking juice decreases the glycemic response because fiber in the fruit slows absorption.

 Adding foods with sugars to the diet may produce a lower glycemic response if these foods are eaten with foods that are more slowly absorbed.

Patients can create their own glycemic index by monitoring their blood glucose level after ingesting a particular food. This can help patients improve blood glucose levels through individualized manipulation of the diet. Many patients who use frequent monitoring of blood glucose levels can use this information to adjust their insulin doses for variations in food intake.

Other Dietary Concerns

ALCOHOL CONSUMPTION

Patients with diabetes do not need to give up alcoholic beverages entirely, but patients and health care professionals need to be aware of the potential adverse effects of alcohol specific to diabetes. In general, the same precautions regarding the use of alcohol by people without diabetes should be applied to patients with diabetes. Moderation is recommended. The main danger of alcohol consumption by a diabetic patient is hypoglycemia, especially for patients who take insulin. Alcohol may decrease the normal physiologic reactions in the body that produce glucose (gluconeogenesis). Thus, if a diabetic patient takes alcohol on an empty stomach, there is an increased likelihood that hypoglycemia will develop. In addition, excessive alcohol intake may impair the patient’s ability to recognize and treat hypoglycemia and to follow a prescribed meal plan to prevent hypoglycemia. To reduce the risk of hypoglycemia, the patient should be cautioned to eat while drinking alcohol (ADA, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2003).

For the person with type 2 diabetes treated with the sulfonylurea agent chlorpropamide (Diabinese), a potential side effect of alcohol consumption is a disulfiram (Antabuse) type of reaction, which involves facial flushing, warmth, headache, nausea, vomiting, sweating, or thirst within minutes of consuming alcohol. The intensity of the reaction depends on the amount of alcohol consumed; the reaction seems to be less common with other sulfonylureas. Alcohol consumption may lead to excessive weight gain (from the high caloric content of alcohol), hyperlipidemia, and elevated glucose levels (especially with mixed drinks and liqueurs). Patient teaching regarding alcohol intake must emphasize moderation in the amount of alcohol consumed. Lower-calorie or less sweet drinks, such as light beer or dry wine, and food intake along with alcohol consumption are advised. For patients with type 2 diabetes especially, incorporating the calories from alcohol into the overall meal plan is important for weight control.

SWEETENERS

Using sweeteners is acceptable for patients with diabetes, especially if it assists in overall dietary adherence. Moderation in the amount of sweetener used is encouraged to avoid potential adverse effects. There are two main types of sweeteners: nutritive and non-nutritive. The nutritive sweeteners contain calories, and the non-nutritive sweeteners have few or no calories in the amounts normally used. Nutritive sweeteners include fructose (fruit sugar), sorbitol, and xylitol. They are not calorie-free; they provide calories in amounts similar to those in sucrose (table sugar). They cause less elevation in blood sugar levels than sucrose and are often used in “sugar-free” foods. Sweeteners containing sorbitol may have a laxative effect. Non-nutritive sweeteners have minimal or no calories. They are used in food products and are also available for table use. They produce minimal or no elevation in blood glucose levels and have been approved by the Food and Drug Administration as safe for people with diabetes. Saccharin contains no calories. Aspartame (NutraSweet) is packaged with dextrose; it contains 4 calories per packet and loses sweetness with heat. Acesulfame-K (Sunnette) is also packaged with dextrose; it contains 1 calorie per packet. Sucralose (Splenda) is a newer non-nutritive, high-intensity sweetener that is about 600 times sweeter than sugar. The Food and Drug Administration has approved it for use in baked goods, nonalcoholic beverages, chewing gum, coffee, confections, frostings, and frozen dairy products.

MISLEADING FOOD LABELS

Foods labeled “sugarless” or “sugar-free” may still provide calories equal to those of the equivalent sugar-containing products if they are made with nutritive sweeteners. Thus, for weight loss, these products may not always be useful. In addition, patients must not consider them “free” foods to be eaten in unlimited quantity, because they may elevate blood glucose levels. Foods labeled “dietetic” are not necessarily reduced-calorie foods. They may be lower in sodium or have other special dietary uses. Patients are advised that foods labeled “dietetic” may still contain significant amounts of sugar or fat. Patients must also be taught to read the labels of “health foods”—especially snacks—because they often contain carbohydrates such as honey, brown sugar, and corn syrup. In addition, these supposedly healthy snacks frequently contain saturated vegetable fats (eg, coconut or palm oil), hydrogenated vegetable fats, or animal fats, which may be contraindicated in patients with elevated blood lipid levels.

EXERCISE Benefits

Exercise is extremely important in managing diabetes because of its effects on lowering blood glucose and reducing cardiovascular risk factors. Exercise lowers the blood glucose level by increasing the uptake of glucose by body muscles and by improving insulin utilization. It also improves circulation and muscle tone. Resistance (strength) training, such as weight lifting, can increase lean muscle mass, thereby increasing the resting metabolic rate. These effects are useful in diabetes in relation to losing weight, easing stress, and maintaining a feeling of well-being. Exercise also alters blood lipid levels, increasing levels of high-density lipoproteins and decreasing total cholesterol and triglyceride levels. This is especially important to the person with diabetes because of the increased risk of cardiovascular disease (Creviston & Quinn, 2001).

Exercise Precautions

Patients who have blood glucose levels exceeding 250 mg/dL (14 mmol/L) and who have ketones in their urine should not begin exercising until the urine tests negative for ketones and the blood glucose level is closer to normal. Exercising with elevated blood glucose levels increases the secretion of glucagon, growth hormone, and catecholamines. The liver then releases more glucose, and the result is an increase in the blood glucose level (ADA, Physical Activity/Exercise and Diabetes Mellitus, 2003). The physiologic decrease in circulating insulin that normally occurs with exercise cannot occur in patients treated with insulin. Initially, the patient who requires insulin should be taught to eat a 15-g carbohydrate snack (a fruit exchange) or a snack of complex carbohydrate with a protein before engaging in moderate exercise, to prevent unexpected hypoglycemia. The exact amount of food needed varies from person to person and should be determined by blood glucose monitoring. Some patients find that they do not require a pre-exercise snack if they exercise within 1 to 2 hours after a meal. Other patients may require extra food regardless of when they exercise. If extra food is required, it need not be deducted from the regular meal plan. Another potential problem for patients who take insulin is hypoglycemia that occurs many hours after exercise.

To avoid postexercise hypoglycemia, especially after strenuous or prolonged exercise, the patient may need to eat a snack at the end of the exercise session and at bedtime and monitor the blood glucose level more frequently. In addition, it may be necessary to have the patient reduce the dosage of insulin that peaks at the time of exercise. Patients who are capable, knowledgeable, and responsible can learn to adjust their own insulin doses. Others need specific instructions on what to do when they exercise. Patients participating in extended periods of exercise should test their blood glucose levels before, during, and after the exercise period, and they should snack on carbohydrates as needed to maintain blood glucose levels (ADA, Physical Activity/Exercise and Diabetes Mellitus, 2003). Other participants or observers should be aware that the person exercising has diabetes, and they should know what assistance to give if severe hypoglycemia occurs. In obese people with type 2 diabetes, exercise in addition to dietary management both improves glucose metabolism and enhances loss of body fat. Exercise coupled with weight loss improves insulin sensitivity and may decrease the need for insulin or oral agents. Eventually, the patient’s glucose tolerance may return to normal. The patient with type 2 diabetes who is not taking insulin or an oral agent may not need extra food before exercise.

Exercise Recommendations

People with diabetes should exercise at the same time (preferably when blood glucose levels are at their peak) and in the same amount each day. Regular daily exercise, rather than sporadic exercise, should be encouraged. Exercise recommendations must be altered as necessary for patients with diabetic complications such as retinopathy, autonomic neuropathy, sensorimotor neuropathy, and cardiovascular disease (ADA, Physical Activity/Exercise and Diabetes Mellitus, 2003). Increased blood pressure associated with exercise may aggravate diabetic retinopathy and increase the risk of a hemorrhage into the vitreous or retina. Patients with ischemic heart disease risk triggering angina or a myocardial infarction, which may be silent. Avoiding trauma to the lower extremities is especially important in the patient with numbness related to neuropathy. In general, a slow, gradual increase in the exercise period is encouraged. For many patients, walking is a safe and beneficial form of exercise that requires no special equipment (except for proper shoes) and can be performed anywhere. People with diabetes should discuss an exercise program with their physician and undergo a careful medical evaluation with appropriate diagnostic studies before beginning an exercise program (ADA, Physical Activity/Exercise and Diabetes Mellitus, 2003; Creviston & Quinn, 2001; Flood & Constance, 2002). For patients who are older than 30 years and who have two or more risk factors for heart disease, an exercise stress test is recommended. Risk factors for heart disease include hypertension, obesity, high cholesterol levels, abnormal resting electrocardiogram, sedentary lifestyle, smoking, male gender, and a family history of heart disease.

Gerontologic Considerations

Physical activity that is consistent and realistic is beneficial to the elderly person with diabetes. Physical fitness in the elderly population with diabetes may lead to less chronic vascular disease and an improved quality of life (ADA, Physical Activity/Exercise and Diabetes Mellitus, 2003). Advantages of exercise in this population include a decrease in hyperglycemia, a general sense of wellbeing, and the use of ingested calories, resulting in weight reduction. Because there is an increased incidence of cardiovascular problems in the elderly, a pattern of gradual, consistent exercise should be planned that does not exceed the patient’s physical capacity. Physical impairment from other chronic diseases must also be considered. In some cases a physical therapy evaluation may be warranted with the goal of determining exercises specific to the patient’s needs and abilities. Tools such as the “Armchair Fitness” video may be helpful. For more information about agerelated changes that affect diabetes management see Chart 41-6.

 

MONITORING GLUCOSE LEVELS AND KETONES

 

Blood glucose monitoring is a cornerstone of diabetes management, and self-monitoring of blood glucose (SMBG) levels by patients has dramatically altered diabetes care. Frequent SMBG enables people with diabetes to adjust the treatment regimen to obtain optimal blood glucose control. This allows for detection and prevention of hypoglycemia and hyperglycemia and plays a crucial role in normalizing blood glucose levels, which in turn may reduce the risk of long-term diabetic complications. Various SMBG methods are available. Most involve obtaining a drop of blood from the fingertip, applying the blood to a special reagent strip, and allowing the blood to stay on the strip for the amount of time specified by the manufacturer (usually 5 to 30 seconds). The meter gives a digital readout of the blood glucose value.

The meters available for SMBG offer different features and benefits. Newer monitors have eliminated the step of blood removal from the strip. The strip is placed in the meter first, before blood is applied to it. Once the blood is placed on the strip, it remains there for the duration of the test. The meter automatically displays the blood glucose level after a short time (less than 1 minute). Some meters are biosensors that use blood obtained from alternate test sites, such as the forearm. They have a special lancing device that is useful for patients who have painful fingertips or pain with finger sticks. Some meters can be used by patients with visual impairments. They have audio components that assist the patient in performing the test and obtaining the result. In addition, meters are available to check both blood glucose and blood ketone levels by those who are particularly susceptible to development of DKA.

Advantages and Disadvantages of SMBG Systems

The monitoring method used by the patient must match his or her skill level. Factors affecting SMBG performance include visual acuity, fine motor coordination, cognitive ability, comfort with technology, willingness, and cost. Visual methods are the least expensive and require less equipment. However, they require the ability to distinguish colors and to be exact in timing the procedures. Further, they involve subjective interpretation of results. Monitoring blood glucose using meters is recommended because meters have become much less expensive and less technique-dependent, making the results more accurate. Referral to a social worker may be warranted to assist individuals without the financial means to purchase a meter. Older meters that required removal of blood from the reagent strip are generally obsolete. These procedures have more steps that must be performed in an exact sequence. The newer meters that do not require removal of blood from the strip generally are easier to use. However, most do not provide a backup method for visually assessing the meter results. Figure 41-3 illustrates a system for glucose monitoring. A potential hazard of all SMBG methods is that the patient may obtain and report erroneous blood glucose values as a result of using incorrect techniques.

Some common sources of error include:

Improper application of blood (eg, drop too small)

 Improper meter cleaning and maintenance (eg, allowing dust or blood to accumulate on the optic window). This is not an issue in the biosensor type of meter.

 Damage to the reagent strips by heat or humidity; use of outdated strips

 The nurse plays an important role in providing initial teaching about SMBG techniques. Equally important is evaluating the techniques of patients who are experienced in self-monitoring. Patients should be discouraged from purchasing SMBG products from stores or catalogs that do not provide direct education. Every 6 to 12 months, patients should conduct a comparison of their meter with a simultaneous laboratory-measured blood glucose level in their physician’s office. The accuracy of the meter and strips should also be assessed with control solutions specific to that meter whenever a new vial of strips is used or whenever the validity of the reading is in doubt.

Candidates for SMBG

For everyone with diabetes, SMBG is useful for managing selfcare. It is a key component of treatment for any intensive insulin therapy regimen (including two to four injections per day or insulin pumps) and for diabetes management during pregnancy. It is also recommended for patients with: Unstable diabetes A tendency for severe ketosis or hypoglycemia Hypoglycemia without warning symptoms For patients not taking insulin, SMBG is helpful for monitoring the effectiveness of exercise, diet, and oral antidiabetic agents. It can also help motivate patients to continue with treatment. For patients with type 2 diabetes, SMBG is recommended during periods of suspected hyperglycemia (eg, illness) or hypoglycemia (eg, unusual increased activity levels) (ADA, Physical Activity/Exercise and Diabetes Mellitus, 2003).

Frequency of SMBG

For most patients who require insulin, SMBG is recommended two to four times daily (usually before meals and at bedtime). For patients who take insulin before each meal, SMBG is required at least three times daily before meals to determine each dose (ADA, Tests of Glycemia in Diabetes, 2002). Patients not receiving insulin may be instructed to assess their blood glucose levels at least two or three times per week, including a 2-hour postprandial test. For all patients, testing is recommended whenever hypoglycemia or hyperglycemia is suspected. The patient should increase the frequency of SMBG with changes in medications, activity, or diet and with stress or illness.

Responding to SMBG Results

Patients are instructed to keep a record or logbook of blood glucose levels so that they can detect patterns. Testing is done at the peak action time of the medication to evaluate the need for dosage adjustments. To evaluate basal insulin and determine bolus insulin doses, testing is performed before meals. To titrate bolus insulin doses, regular or lispro, testing is done 2 hours after meals. Patients with type 2 diabetes are encouraged to test before and 2 hours after the largest meal of the day. Patients who take insulin at bedtime or who are on an insulin infusion pump must also test at 3 a.m. once a week to document that the blood glucose level is not decreasing during the night. If a patient is unwilling or cannot afford to test frequently, then once or twice a day may be sufficient if the patient varies the time of day to test (eg, before breakfast one day, before lunch the next day). A tendency to discontinue SMBG is more likely to occur when patients do not receive instruction about using the results to alter their treatment regimen. Instructions vary according to the patient’s understanding and the physician’s philosophy of diabetes management. At the very least, patients should be given parameters for calling the physician. Patients using intensive insulin therapy regimens may be instructed in the use of algorithms (rules or decision trees) for changing the insulin doses based on patterns of values greater or less than the target range and the amount of carbohydrate to be consumed. Baseline patterns should be established by SMBG for 1 to 2 weeks.

Glycosylated Hemoglobin

Glycosylated hemoglobin (referred to as HgbA1C or A1C) is a blood test that reflects average blood glucose levels over a period of approximately 2 to 3 months (ADA, Tests of Glycemia in Diabetes, 2003). When blood glucose levels are elevated, glucose molecules attach to hemoglobin in the red blood cell. The longer the amount of glucose in the blood remains above normal, the more glucose binds to the red blood cell and the higher the glycosylated hemoglobin level. This complex (the hemoglobin attached to the glucose) is permanent and lasts for the life of the red blood cell, approximately 120 days. If near-normal blood glucose levels are maintained, with only occasional increases in blood glucose, the overall value will not be greatly elevated. However, if the blood glucose values are consistently high, then the test result will also be elevated. If patients report mostly normal SMBG results but the glycosylated hemoglobin is high, there may be errors in the methods used for glucose monitoring, errors in recording results, or frequent elevations in glucose levels at times during the day when the patient is not usually monitoring the blood. Various tests measure the same thing but have different names, including hemoglobin A1C and hemoglobin A1. The normal values differ slightly from test to test and from laboratory to laboratory and normally range from 4% to 6%. Values within the normal range indicate consistently near-normal blood glucose levels, a goal made easier by SMBG.

Urine Testing for Glucose

Before SMBG methods were available, urine glucose testing was the only way to monitor diabetes on a daily basis. Today its use is limited to patients who cannot or will not perform SMBG. The advantages of urine glucose testing are that it is less expensive than SMBG and it is not invasive. The general procedure involves applying urine to a reagent strip or tablet and matching colors on the strip with a color chart at the end of a specified period.

Disadvantages of urine testing include the following:

Results do not accurately reflect the blood glucose level at the time of the test.

 The renal threshold for glucose is 180 to 200 mg/dL (9.9 to 11.1 mmol/L), far above target blood glucose levels.

Hypoglycemia cannot be detected because a “negative” urine glucose result may occur when the blood glucose level ranges from 0 to 180 mg/dL (9.9 mmol/L) or higher.

Patients may have a false sense of being in good control when results are always negative.

Various medications (eg, aspirin, vitamin C, some antibiotics) may interfere with test results.

In elderly patients and patients with kidney disease, the renal threshold (the level of blood glucose at which glucose starts to appear in the urine) is raised; thus, false-negative readings may occur at dangerously elevated glucose levels.

Testing for Ketones

Ketones (or ketone bodies) in the urine signal that control of type 1 diabetes is deteriorating, and the risk of DKA is high. When there is almost no effective insulin available, the body starts to break down stored fat for energy. Ketone bodies are byproducts of this fat breakdown, and they accumulate in the blood and urine. Urine testing is the most common method used for self-testing of ketone bodies by patients. A meter that enables testing of blood for ketones is available but not widely used. Most commonly, patients use a urine dipstick (Ketostix or Chemstrip uK) to detect ketonuria. The reagent pad on the strip turns purplish when ketones are present. (One of the ketone bodies is called acetone, and this term is frequently used interchangeably with the term “ketones.”) Other strips are available for measuring both urine glucose and ketones (Keto-Diastix or Chemstrip uGK). Large amounts of ketones may depress the color response of the glucose test area. Urine ketone testing should be performed whenever patients with type 1 diabetes have glucosuria or persistently elevated blood glucose levels (more than 240 mg/dL or 13.2 mmol/L for two testing periods in a row) and during illness, in pregnancy with pre-existing diabetes, and in gestational diabetes (ADA, Tests of Glycemia in Diabetes, 2003).

PHARMACOLOGIC THERAPY

As stated earlier, insulin is secreted by the beta cells of the islets of Langerhans and works to lower the blood glucose level after meals by facilitating the uptake and utilization of glucose by muscle, fat, and liver cells. In the absence of adequate insulin, pharmacologic therapy is essential.

Insulin Therapy and Insulin Preparations

Daily insulin

 

Because the body loses the ability to produce insulin in type 1 diabetes, exogenous insulin must be administered for life. In type 2 diabetes, insulin may be necessary on a long-term basis to control glucose levels if diet and oral agents fail. In addition, some patients in whom type 2 diabetes is usually controlled by diet alone or by diet and an oral agent may require insulin temporarily during illness, infection, pregnancy, surgery, or some other stressful event. In many cases, insulin injections are administered two or more times daily to control the blood glucose level. Because the insulin dose required by the individual patient is determined by the level of glucose in the blood, accurate monitoring of blood glucose levels is essential; thus, SMBG has become a cornerstone of insulin therapy. A number of insulin preparations are available. They vary according to three main characteristics: time course of action, species (source), and manufacturer.

TIME COURSE OF ACTION

Insulin may be grouped into several categories based on the onset, peak, and duration of action. Human insulin preparations have a shorter duration of action than insulin from animal sources because the presence of animal proteins triggers an immune response that results in the binding of animal insulin, which slows its availability. Rapid-acting insulins such as insulin lispro (Humalog) and insulin aspart (Novolog) are blood glucose-lowering agents that produce a more rapid effect that is of shorter duration than regular insulin. These insulins have an onset of 5 to 15 minutes, a peak action of 1 hour after injection, and a duration of 2 to 4 hours. Because of their rapid onset, patients should be instructed to eat no more than 5 to 15 minutes after injection. Because of the short duration of action of these insulin analogs, patients with type 1 diabetes and some patients with type 2 or gestational diabetes also require a long-acting insulin to maintain glucose control. Basal insulin is necessary to maintain blood glucose levels irrespective of meals. A constant level of insulin is required at all times. Intermediate-acting insulins function as basal insulins but may have to be split into two injections to achieve 24-hour coverage. Short-acting insulins, called regular insulin (marked R on the bottle), have an onset of 30 minutes to 1 hour; peak, 2 to 3 hours; and duration, 4 to 6 hours. Regular insulin is a clear solution and is usually administered 20 to 30 minutes before a meal, either alone or in combination with a longer-acting insulin. Humulin R, Iletin Regular, and Novolin R are examples of regular insulin. Intermediate-acting insulins, called NPH insulin (neutral protamine Hagedorn) or Lente insulin, have an onset of 3 to 4 hours; peak, 4 to 12 hours; and duration, 16 to 20 hours. Intermediateacting insulins, which are similar in their time course of action, appear white and cloudy. If NPH or Lente insulin is taken alone, it is not crucial that it be taken 30 minutes before the meal. It is important, however, for the patient to eat some food around the time of the onset and peak of these insulins. Humulin N, Iletin NPH, and Novolin N are examples of NPH insulins; Humulin L, Iletin L, and Novolin L are examples of Lente insulins. Long-acting insulins, called Ultralente insulin, are sometimes referred to as peakless insulins because they tend to have a long, slow, sustained action rather than sharp, definite peaks in action. The onset of long-acting human insulin is 6 to 8 hours; peak, 12 to 16 hours; and duration, 20 to 30 hours. “Peakless” basal insulin, insulin glargine (Lantus), is approved for use as a basal insulin—that is, the insulin is absorbed very slowly over 24 hours and can be given once a day. Because the insulin is in a suspension with a pH of 4, it cannot be mixed with other insulins because this would cause precipitation. It is given once a day at bedtime. In the future, “inhaled insulin” may be approved for use. This type of insulin is in the form of a very fine powder, which is inhaled through a device similar to that used to administer asthma medications. The patient’s program would consist of a “basal” rate of insulin such as glargine supplemented by an inhaled dose before each meal. The nurse may find that different sources list differing numbers of hours for the onset, peak, and duration of action of the main types of insulin, and patients’ responses may vary (ie, larger doses prolong onset, duration, and peak). The nurse should focus on which meals—and snacks—are being “covered” by which insulin doses. In general, the rapid- and short-acting insulins are expected to cover the rise in glucose levels after meals, immediately after the injection; the intermediate-acting insulins are expected to cover subsequent meals; and the long-acting insulins provide a relatively constant level of insulin and act as a basal insulin.

SPECIES (SOURCE)

In the past, all insulins were obtained from beef (cow) and pork (pig) pancreases. “Human insulins” are now widely available. They are produced by recombinant DNA technology and have largely replaced insulin from animal sources (ADA, Insulin Administration, 2003).

MANUFACTURER

The two manufacturers of insulin in the United States are Eli- Lilly and Novo Nordisk. The insulins made by the different companies are usually interchangeable, provided the concentration (eg, U-100), species (eg, human), and type (eg, NPH) of insulin are the same. Human insulins made by different companies have different brand names. Therefore, a patient taking 20 units human NPH insulin may be using either Humulin N or Novolin N.

 

Insulin Regimens

Insulin regimens vary from one to four injections per day. Usually there is a combination of a short-acting insulin and a longeracting insulin. The normally functioning pancreas continuously secretes small amounts of insulin during the day and night. In addition, whenever blood glucose rises after ingestion of food, there is a rapid burst of insulin secretion in proportion to the glucoseraising effect of the food. The goal of all but the simplest, oneinjection insulin regimens is to mimic this normal pattern of insulin secretion in response to food intake and activity patterns.

Patients can learn to use SMBG results and carbohydrate counting to vary the insulin doses. This allows patients more flexibility in the timing and content of meals and exercise periods. However, complex insulin regimens require a strong level of commitment, intensive education, and close follow-up by the health care team. In addition, patients aiming for normal blood glucose levels run the risk of more hypoglycemic reactions. The type of regimen used by any particular patient varies. For example, patient knowledge, willingness, goals, health status, and finances all may affect decisions regarding insulin treatment. In addition, the physician’s philosophy about blood glucose control and the availability of equipment and support staff may influence decisions regarding insulin therapy. There are two general approaches to insulin therapy: conventional and intensive.

CONVENTIONAL REGIMEN

One approach is to simplify the insulin regimen as much as possible, with the aim of avoiding the acute complications of diabetes (hypoglycemia and symptomatic hyperglycemia). With this type of simplified regimen (eg, one or more injections of a mixture of short- and intermediate-acting insulins per day), patients may frequently have blood glucose levels well above normal. The exception is the patient who never varies meal patterns and activity levels. This approach would be appropriate for the terminally ill, the frail elderly with limited self-care abilities, or any patient who is completely unwilling or unable to engage in the self-management activities that are part of a more complex insulin regimen.

INTENSIVE REGIMEN

The second approach is to use a more complex insulin regimen to achieve as much control over blood glucose levels as is safe and practical. The results of the landmark DCCT study (1993) and the UKPDS study (1998) have demonstrated that maintaining blood glucose levels as close to normal as possible prevents or slows the progression of long-term diabetic complications. Another reason for using a more complex insulin regimen is to allow patients more flexibility to change their insulin doses from day to day in accordance with changes in their eating and activity patterns, with stress and illness, and as needed for variations in the prevailing glucose level. Although the DCCT found that intensive treatment (three or four injections of insulin per day) reduced the risk of complications, not all people with diabetes are candidates for very tight control of blood glucose. The risk for severe hypoglycemia was increased threefold in patients receiving intensive treatment in the DCCT (ADA, Implications of the Diabetes Control and Complications Trial, 2003).

Those who may not be candidates include patients with:

Nervous system disorders rendering them unaware of hypoglycemic episodes (eg, those with autonomic neuropathy)

Recurring severe hypoglycemia

Irreversible diabetic complications, such as blindness or end-stage renal disease

 Cerebrovascular and/or cardiovascular disease

Ineffective self-care skills

An exception is the patient who has received a kidney transplant because of nephropathy and chronic renal failure; this patient should be on an intensive regimen to preserve function of the new kidney. The patient needs to be involved in the decision regarding which insulin regimen to use. Patients need to compare the potential benefits of different regimens with the potential costs (eg, time involved, number of injections or finger sticks for glucose testing, amount of record-keeping). There are no set guidelines as to which insulin regimen should be used for which patients. It must not be assumed that an elderly patient or a patient with visual impairment should automatically be given a simplified regimen. Likewise, it must not be assumed that all people will want to be involved in a complex treatment regimen. Nurses play an important role in educating patients about the different approaches to insulin therapy. Nurses should refer patients to diabetes specialists or diabetes education centers, when available, for further training and education in the various insulin treatment regimens.

Complications of Insulin Therapy

LOCAL ALLERGIC REACTIONS

A local allergic reaction (redness, swelling, tenderness, and induration or a 2- to 4-cm wheal) may appear at the injection site 1 to 2 hours after the insulin administration. These reactions, which usually occur during the beginning stages of therapy and disappear with continued use of insulin, are becoming rare because of the increased use of human insulins. The physician may prescribe an antihistamine to be taken 1 hour before the injection if such a local reaction occurs.

SYSTEMIC ALLERGIC REACTIONS

Systemic allergic reactions to insulin are rare. When they do occur, there is an immediate local skin reaction that gradually spreads into generalized urticaria (hives). The treatment is desensitization, with small doses of insulin administered in gradually increasing amounts using a desensitization kit. These rare reactions are occasionally associated with generalized edema or anaphylaxis.

INSULIN LIPODYSTROPHY

Lipodystrophy refers to a localized reaction, in the form of either lipoatrophy or lipohypertrophy, occurring at the site of insulin injections. Lipoatrophy is loss of subcutaneous fat and appears as slight dimpling or more serious pitting of subcutaneous fat. The use of human insulin has almost eliminated this disfiguring complication. Lipohypertrophy, the development of fibrofatty masses at the injection site, is caused by the repeated use of an injection site. If insulin is injected into scarred areas, absorption may be delayed.

 This is one reason that rotation of injection sites is so important. The patient should avoid injecting insulin into these areas until the hypertrophy disappears.

INSULIN RESISTANCE

Most patients at one time or another have some degree of insulin resistance. This may occur for various reasons, the most common being obesity, which can be overcome by weight loss. Clinical insulin resistance has been defined as a daily insulin requirement of 200 units or more. In most diabetic patients taking insulin, immune antibodies develop and bind the insulin, thereby decreasing the insulin available for use. All animal insulins, as well as human insulins to a lesser degree, cause antibody production in humans. Very few resistant patients develop high levels of antibodies. Many of these patients have a history of insulin therapy interrupted for several months or more. Treatment consists of administering a more concentrated insulin preparation, such as U500, which is available by special order. Occasionally, prednisone is needed to block the production of antibodies. This may be followed by a gradual reduction in insulin requirement. Therefore, patients need to monitor themselves for hypoglycemia.

MORNING HYPERGLYCEMIA

An elevated blood glucose level upon arising in the morning may be caused by an insufficient level of insulin due to several causes: the dawn phenomenon, the Somogyi effect, or insulin waning. The dawn phenomenon is characterized by a relatively normal blood glucose level until approximately 3 a.m., when blood glucose levels begin to rise. The phenomenon is thought to result from nocturnal surges in growth hormone secretion that create a greater need for insulin in the early morning hours in patients with type 1 diabetes. It must be distinguished from insulin waning (the progressive increase in blood glucose from bedtime to morning) or the Somogyi effect (nocturnal hypoglycemia followed by rebound hyperglycemia). Insulin waning is frequently seen if the evening NPH dose is administered before dinner and is prevented by moving the evening dose of NPH insulin to bedtime. It may be difficult to tell from the patient’s history which of these causes is responsible for morning hyperglycemia. To determine the cause, the patient must be awakened once or twice during the night to test blood glucose levels. Testing the blood glucose level at bedtime, at 3 a.m., and on awakening provides information that can be used in making adjustments in insulin to avoid morning hyperglycemia caused by the dawn phenomenon. Table 41-5 summarizes the differences among insulin waning, the dawn phenomenon, and the Somogyi effect.

Alternative Methods of Insulin Delivery

INSULIN PENS

These devices use small (150- to 300-unit) prefilled insulin cartridges that are loaded into a penlike holder. A disposable needle is attached to the device for insulin injection. Insulin is delivered by dialing in a dose or pushing a button for every 1- or 2-unit increment administered. People using these devices still need to insert the needle for each injection; however, they do not need to carry insulin bottles or to draw up insulin before each injection. These devices are most useful for patients who need to inject only one type of insulin at a time (eg, premeal regular insulin three times a day and bedtime NPH insulin) or who can use the premixed insulins. These pens are convenient for those who administer insulin before dinner if eating out or traveling. They are also useful for patients with impaired manual dexterity, vision, or cognitive function that makes the use of traditional syringes difficult.

JET INJECTORS

As an alternative to needle injections, jet injection devices deliver insulin through the skin under pressure in an extremely fine stream. These devices are more expensive than other alternative devices mentioned above and require thorough training and supervision when first used. In addition, patients should be cautioned that absorption rates, peak insulin activity, and insulin levels may be different when changing to a jet injector. (Insulin administered by jet injector is usually absorbed faster.) Bruising has occurred in some patients with use of the jet injector.

Insulin Pump

 

INSULIN PUMPS

Continuous subcutaneous insulin infusion involves the use of small, externally worn devices that closely mimic the functioning of the normal pancreas (ADA, Continuous Subcutaneous Insulin Infusion, 2003). Insulin pumps contain a 3-mL syringe attached to a long (24- to 42-in), thin, narrow-lumen tube with a needle or Teflon catheter attached to the end (Figs. 41-4 and 41-5). The patient inserts the needle or catheter into the subcutaneous tissue (usually on the abdomen) and secures it with tape or a transparent dressing. The needle or catheter is changed at least every 3 days. The pump is then worn either on a belt or in a pocket. Some women keep the pump tucked into the front or side of the bra or wear it on a garter belt on the thigh. The rapid-acting lispro insulin is used in the insulin pump and is delivered at a basal rate and as a bolus with meals. A continuous basal rate of insulin is typically 0.5 to 2.0 units/hour, depending on the patient’s needs. A bolus dose of insulin is delivered before each meal when the patient activates the pump (by pushing buttons). The patient determines the amount of insulin to infuse based on blood glucose levels and anticipated food intake and activity level. Advantages of insulin pumps include increased flexibility in lifestyle (in terms of timing and amount of  meals, exercise, and travel) and, for many patients, improved blood glucose control. A disadvantage of insulin pumps is that unexpected disruptions in the flow of insulin from the pump may occur if the tubing or needle becomes occluded, if the supply of insulin runs out, or if the battery is depleted, increasing the risk of DKA. Effective teaching and a knowledgeable patient can minimize this risk. Another disadvantage is the potential for infection at needle insertion sites. Hypoglycemia may occur with insulin pump therapy; however, this is usually related to the lowered blood glucose levels many patients achieve rather than to a specific problem with the pump itself. The tight diabetic control associated with using an insulin pump may increase the incidence of hypoglycemia unawareness because of the very gradual decline in serum glucose level from levels greater than 70 mg/dL (3.9 mmol/L) to those less than 60 mg/dL (3.3 mmol/L). Some patients find that wearing the pump for 24 hours each day is an inconvenience. However, the pump can easily be disconnected, per patient preference, for limited periods (eg, for showering, exercise, or sexual activity). Insulin pump candidates must be willing to assess blood glucose levels multiple times daily while on pump therapy. In addition, they must be psychologically stable and open about having diabetes, because the insulin pump is often a visible sign to others and a constant reminder to the patient that he or she has diabetes. Most important, patients using insulin pumps must have extensive education in the use of the insulin pump and in selfmanagement of blood glucose and insulin doses. They must work closely with a team of health care professionals who are experienced in insulin pump therapy—specifically, a diabetologist/ endocrinologist, a dietitian, and a certified diabetes educator. Many insurance policies cover the cost of pump therapy; if it is not covered, the extra expense of the pump and associated supplies may be a deterrent for some patients. Medicare now covers insulin pump therapy for the patient with type 1 diabetes.

IMPLANTABLE AND INHALANT INSULIN DELIVERY

Research into mechanical delivery of insulin has involved implantable insulin pumps that can be externally programmed according to blood glucose test results. Clinical trials with these devices are continuing. In addition, there is research into the development of implantable devices that both measure the blood glucose level and deliver insulin as needed. Methods of administering insulin by the oral route (oral spray or capsule), skin patch, and inhalation are undergoing intensive study.

TRANSPLANTATION OF PANCREATIC CELLS

Transplantation of the whole pancreas or a segment of the pancreas is being performed on a limited population (mostly diabetic patients receiving kidney transplantations simultaneously). One main issue regarding pancreatic transplantation is weighing the risks of antirejection medications against the advantages of pancreas transplantation. Another approach under investigation is the implantation of insulin-producing pancreatic islet cells (ADA, Pancreas Transplantation for Patients With Type 1 Diabetes, 2003). This latter approach involves a less extensive surgical procedure and a potentially lower incidence of immunogenic problems. However, thus far, independence from exogenous insulin has been limited to 2 years after transplantation of islet cells. A recent study of patients with islet cell transplants using less toxic antirejection drugs has shown promise (Shapiro et al., 2000).

Oral Antidiabetic Agents

Oral antidiabetic agents may be effective for patients who have type 2 diabetes that cannot be treated by diet and exercise alone; however, they cannot be used during pregnancy. In the United States, oral antidiabetic agents include the sulfonylureas, biguanides, alpha glucosidase inhibitors, thiazolidinediones, and meglitinides (Table 41-6). Sulfonylureas and meglitinides are considered insulin secretagogues because their action increases the secretion of insulin by the pancreatic beta cells.

SULFONYLUREAS

The sulfonylureas exert their primary action by directly stimulating the pancreas to secrete insulin. Therefore, a functioning pancreas is necessary for these agents to be effective, and they cannot be used in patients with type 1 diabetes. These agents improve insulin action at the cellular level and may also directly decrease glucose production by the liver. The sulfonylureas can be divided into first- and second-generation categories (see Table 41-6). The most common side effects of these medications are GI symptoms and dermatologic reactions. Hypoglycemia may occur when an excessive dose of a sulfonylurea is used or when the patient omits or delays meals, reduces food intake, or increases activity. Because of the prolonged hypoglycemic effects of these agents (especially chlorpropamide), some patients need to be hospitalized for treatment of oral agent-induced hypoglycemia. Another side effect of chlorpropamide is a disulfiram (Antabuse) type of reaction when alcohol is ingested (see section on alcohol consumption for more information). Some medications may directly interact with sulfonylureas, potentiating their hypoglycemic effects (eg, sulfonamides, chloramphenicol, clofibrate, phenylbutazone, and bishydroxycoumarin). In addition, certain medications may independently affect blood glucose levels, thereby indirectly interfering with these agents. Medications that may increase glucose levels include potassium-losing diuretics, corticosteroids, estrogen compounds, and diphenylhydantoin (Dilantin). Medications that may cause hypoglycemia include salicylates, propranolol, monoamine oxidase inhibitors, and pentamidine. Second-generation sulfonylureas have the advantage of a shorter half-life and excretion by both the kidney and the liver. This makes these medications safer to use in the elderly, in whom accumulation of the medication can cause recurring hypoglycemia.

BIGUANIDES

The biguanides are other kinds of oral antidiabetic agents. Metformin (Glucophage) produces its antidiabetic effects by facilitating insulin’s action on peripheral receptor sites. Therefore, it can be used only in the presence of insulin. Biguanides have no effect on pancreatic beta cells. Biguanides used with a sulfonylurea may enhance the glucose-lowering effect more than either medication used alone. Lactic acidosis is a potential and serious complication of biguanide therapy; the patient must be monitored closely when therapy is initiated or when dosage changes. Medications that may interact with biguanides include anticoagulants, corticosteroids, diuretics, and oral contraceptives. Metformin is contraindicated in patients with renal impairment (serum creatinine level more than 1.4) or those at risk for renal dysfunction (eg, those with acute myocardial infarction). Renal function studies should be performed periodically to ensure that function is not impaired. Metformin should not be administered for 2 days before any diagnostic testing that may require use of a contrast agent. These situations increase the risk for lactic acidosis. An extended-release form and a combination form (Glucovance) combines metformin with a sulfonylurea, such as glyburide. The combination provides two mechanisms of action and improved patient compliance. Hypoglycemia is a risk.

ALPHA GLUCOSIDASE INHIBITORS

Acarbose (Precose) and miglitol (Glyset) are oral alpha glucosidase inhibitors used in type 2 diabetes management. They work by delaying the absorption of glucose in the intestinal system, resulting in a lower postprandial blood glucose level. As a consequence of plasma glucose reduction, hemoglobin A1C levels drop. In contrast to the sulfonylureas, acarbose and miglitol do not enhance insulin secretion. They can be used alone with dietary treatment as monotherapy or in combination with sulfonylureas, thiazolidinediones, or meglitinides. When these medications are used in combination with sulfonylureas or meglitinides, hypoglycemia may occur. The patient must be advised that if hypoglycemia occurs, sucrose absorption will be blocked and treatment for hypoglycemia should be in the form of glucose, such as glucose tablets. The advantage of oral alpha glucosidase inhibitors is that they are not systemically absorbed and are safe to use. Their side effects are diarrhea and flatulence. These effects may be minimized by starting at a very low dose and increasing the dose gradually. Because acarbose and miglitol affect food absorption, they must be taken immediately before a meal, making therapeutic adherence a potential problem.

THIAZOLIDINEDIONES

Rosiglitizone (Avandia) and pioglitozone (Actos) are oral diabetes medications categorized as thiazolidinediones. They are indicated for patients with type 2 diabetes who take insulin injections and whose blood glucose control is inadequate (hemoglobin A1C level greater than 8.5%). They have also been approved as firstline agents to treat type 2 diabetes, in combination with diet. Thiazolidinediones enhance insulin action at the receptor site without increasing insulin secretion from the beta cells of the pancreas. These medications may affect liver function; therefore, liver function studies must be performed at baseline and at frequent intervals (monthly for the first 12 months of treatment, and quarterly thereafter). Women should be informed that thiazolidinediones can cause resumption of ovulation in perimenopausal anovulatory women, making pregnancy a possibility.

MEGLITINIDES

Repaglinide (Prandin), an oral glucose-lowering agent of the class of oral agents called meglitinides, lowers the blood glucose level by stimulating insulin release from the pancreatic beta cells. Its effectiveness depends on the presence of functioning beta cells. Therefore, repaglinide is contraindicated in patients with type 1 diabetes. Repaglinide has a fast action and a short duration. It should be taken before each meal to stimulate the release of insulin in response to that meal. It is also indicated for use in combination with metformin in patients whose hyperglycemia cannot be controlled by exercise, diet, and either metformin or repaglinide alone. The principal side effect of repaglinide is hypoglycemia; however, this side effect is less severe and frequent than for a sulfonylurea because repaglinide has a short half-life (approximately 1 hour). Patients must be taught the signs and symptoms of hypoglycemia and should understand that the medication should not be taken unless the patient eats a meal. Repaglinide is supplied in 0.5-, 1-, and 2-mg tablets. Naglitinide (Starlix), another meglitinide, has a very rapid onset and short duration. It should be taken with meals and not taken if the meal is skipped. Hypoglycemia risk is low if taken correctly.

General Considerations for Oral Agents

Patients need to understand that oral agents are prescribed as an addition to (not as a substitute for) other treatment modalities, such as diet and exercise. Use of oral antidiabetic medications may need to be halted temporarily and insulin prescribed if hyperglycemia develops that is attributable to infection, trauma, or surgery. In time, oral antidiabetic agents may no longer be effective in controlling the patient’s diabetes. In such cases, the patient is treated with insulin. Approximately half of all patients who initially use oral antidiabetic agents eventually require insulin. This is referred to as a secondary failure. Primary failure occurs when the blood glucose level remains high a month after initial medication use. Because the mechanisms of action vary (Fig. 41-6), the effect may be enhanced using multidose, multiple medications (Inzucchi et al., 1998). Use of multiple medications with different mechanisms of action is very common today (Quinn, 2001b). Using a combination of oral agents with insulin has been proposed as a treatment for some patients with type 2 diabetes. However, the effectiveness of this approach has not yet been demonstrated. Nursing Management Nursing management of the patient with diabetes can involve treatment of a wide variety of physiologic disorders, depending on the patient’s health status and whether the patient is newly diagnosed or seeks care for an unrelated health problem. Nursing management of the newly diagnosed patient and the patient with diabetes as a secondary diagnosis is presented in subsequent sections of this chapter. Because all diabetic patients must master the concepts and skills necessary for long-term management of diabetes and its potential complications, a solid educational foundation is necessary for competent self-care and is an ongoing focus of nursing care.

EDUCATION

Diabetes mellitus is a chronic illness requiring a lifetime of special self-management behaviors. Because diet, physical activity, and physical and emotional stress affect diabetic control, patients must learn to balance a multitude of factors. They must learn daily self-care skills to prevent acute fluctuations in blood glucose, and they must also incorporate into their lifestyle many preventive behaviors for avoidance of long-term diabetic complications. Diabetic patients must become knowledgeable about nutrition, medication effects and side effects, exercise, disease progression, prevention strategies, blood glucose monitoring techniques, and medication adjustment. In addition, they must learn the skills associated with monitoring and managing diabetes and must incorporate many new activities into their daily routines. An appreciation for the knowledge and skills that diabetic patients must acquire can help the nurse in providing effective patient education and counseling (Beebe & O’Donnell, 2001).

DEVELOPING A DIABETIC TEACHING PLAN

Changes in the health care delivery system as a whole have had a major impact on diabetes education and training. Patients with new-onset type 1 diabetes have much shorter hospital stays or may be managed completely on an outpatient basis; patients with new-onset type 2 diabetes are rarely hospitalized for initial care. There has been a proliferation of outpatient diabetes education and training programs, with increasing support of third-party reimbursement. For some patients, however, exposure to diabetes education during hospitalization may be the only opportunity for learning self-management skills and preventing complications. Many hospitals employ nurses who specialize in diabetes education and management and who are certified by the National Certification Board of Diabetes Educators as Certified Diabetes Educators. However, because of the large number of diabetic patients who are admitted to every unit of a hospital for reasons other than diabetes or its complications, the staff nurse plays a vital role in identifying diabetic patients, assessing self-care skills, providing basic education, reinforcing the teaching provided by the specialist, and referring patients for follow-up care after discharge. Diabetes patient education programs that have been peerreviewed by the ADA as meeting National Standards for Diabetes Education can seek reimbursement for education.

Organizing Information

There are various strategies for organizing and prioritizing the vast amount of information that must be taught to diabetic patients. In addition, many hospitals and outpatient diabetes centers have devised written guidelines, care plans, and documentation forms (often based on guidelines from the ADA) that may be used to document and evaluate teaching. A general approach is to organize information and skills into two main types: basic, initial, or “survival” skills and information, and in-depth (advanced) or continuing education.

TEACHING SURVIVAL SKILLS

This information must be taught to any patient with newly diagnosed type 1 or type 2 diabetes and any patient receiving insulin for the first time. This basic information is literally what the patient must know to survive—that is, to avoid severe hypoglycemic or acute hyperglycemic complications after discharge. An outline of survival information includes: 1. Simple pathophysiology a. Basic definition of diabetes (having a high blood glucose level) b. Normal blood glucose ranges and target blood glucose levels c. Effect of insulin and exercise (decrease glucose) d. Effect of food and stress, including illness and infections (increase glucose) e. Basic treatment approaches 2. Treatment modalities a. Administration of insulin and oral antidiabetes medications b. Diet information (food groups, timing of meals) c. Monitoring of blood glucose and ketones 3. Recognition, treatment, and prevention of acute complications a. Hypoglycemia b. Hyperglycemia 4. Pragmatic information a. Where to buy and store insulin, syringes, and glucose monitoring supplies b. When and how to reach the physician For patients with newly diagnosed type 2 diabetes, emphasis is initially placed on diet. Patients starting to take oral sulfonylureas or meglitinides need to know about detecting, preventing, and treating hypoglycemia. If diabetes has gone undetected for many years, the patient may already be experiencing some chronic diabetic complications. Thus, for some patients with newly diagnosed type 2 diabetes, the basic diabetes teaching must include information on preventive skills, such as foot care and eye care—for example, planning yearly or more frequent complete (dilated eye) examinations by the ophthalmologist and understanding that retinopathy is largely asymptomatic until the advanced stages. Patients also need to realize that once they master the basic skills and information, further diabetes education must be pursued. Acquiring in-depth and advanced diabetes knowledge occurs throughout the patient’s lifetime, both formally through programs of continuing education and informally through experience and sharing of information with other people with diabetes.

PLANNING IN-DEPTH AND CONTINUING EDUCATION

This involves teaching more detailed information related to survival skills (eg, learning to vary diet and insulin and preparing for travel) as well as learning preventive measures for avoiding longterm diabetic complications.

Preventive measures include:

 Foot care

Eye care

General hygiene (eg, skin care, oral hygiene)

Risk factor management (eg, control of blood pressure and blood lipid levels, and normalizing blood glucose levels)

More advanced continuing education may include alternative methods for insulin delivery, such as the insulin pump, and algorithms or rules for evaluating and adjusting insulin doses. For example, patients can be taught to increase or decrease insulin doses based on a several-day pattern of blood glucose levels. The degree of advanced diabetes education to be provided depends on the patient’s interest and ability. However, learning preventive measures (especially foot care and eye care) is mandatory for reducing the occurrence of amputations and blindness in diabetic patients.

Assessing Readiness to Learn

Before initiating diabetes education, the nurse assesses the patient’s (and family’s) readiness to learn (Beebe & O’Donnell, 2001). When patients are first diagnosed with diabetes (or first told of their need for insulin), they often go through various stages of the grieving process. These stages may include shock and denial, anger, depression, negotiation, and acceptance. The amount of time it takes for patients and family members to work through the grieving process varies from patient to patient. They may experience helplessness, guilt, altered body image, loss of self-esteem, and concern about the future. The nurse must assess the patient’s coping strategies and reassure patients and families that feelings of depression and shock are normal. Asking the patient and family about their major concerns or fears is an important way to learn about any misinformation that may be contributing to anxiety. Some common misconceptions regarding diabetes and its treatment are listed in Table 41-7. Simple, direct information should be provided to dispel misconceptions. More information can be provided once the patient masters survival skills. After dispelling misconceptions or answering questions that concern the patient the most, the nurse focuses attention on concrete survival skills. Because of the immediate need for multiple new skills, teaching is initiated as soon as possible after diagnosis. Nurses whose patients are in the hospital rarely have the luxury of waiting until the patient feels ready to learn; short hospital stays necessitate initiation of survival skill education as early as possible. This gives the patient the opportunity to practice skills with supervision by the nurse before discharge. Follow-up by home health nurses is often necessary for reinforcement of survival skills. A major goal of patient teaching is an educated consumer, a patient who is informed about the wide variations in the prices of medications and supplies and about the importance of comparing prices.

Determining Teaching Methods

Maintaining flexibility in teaching approaches is important. Teaching skills and information in a logical sequence is not always the most helpful for patients. For example, many patients fear the injection. Before they learn how to draw up, purchase, store, and mix insulins, they should be taught to insert the needle and inject insulin (or practice with saline solution). Numerous demonstrations by the nurse or practice injections before the patient (or family) gives the first injection may actually increase the patient’s anxiety and fear of self-injection. Once patients have actually performed the injection, most are more prepared to hear and to comprehend other information. (If they then want to practice further using a pillow or an orange, that would be appropriate.) Thus, having patients self-inject first or having patients perform a fingerstick for glucose monitoring first may enhance learning to draw up the insulin or to operate the glucose meter. Ample opportunity should be provided for the patient and family to practice skills under supervision (including selfinjection, self-testing, meal selection, verbalization of symptoms, and treatment of hypoglycemia). Once skills have been mastered, participation in ongoing support groups may assist patients in incorporating new habits and maintaining adherence to the treatment regimen. Various tools can be used to complement teaching. Many of the companies that manufacture products for diabetes self-care also provide booklets and videotapes to assist in patient teaching. It is important to use a variety of written handouts that match the patient’s learning needs (including different languages, lowliteracy information, large print). Patients can continue learning about diabetes care by participating in activities sponsored by local hospitals and diabetes organizations. In addition, magazines with information on all aspects of diabetes management are available for people with diabetes.

IMPLEMENTING THE PLAN

Teaching Experienced Diabetic Patients

The nurse should continue to assess the skills of patients who have had diabetes for many years, because it is estimated that up to 50% of patients may make errors in self-care. Assessment of these patients must include direct observation of skills, not just their self-report of self-care behaviors. In addition, these patients must be fully aware of preventive measures related to foot care, eye care, and risk factor management. If patients are experiencing long-term diabetic complications for the first time, they may go through the grieving process again. Some of these patients may have a renewed interest in diabetes self-care in the hope of delaying further complications. Other patients may be overwhelmed by feelings of guilt and depression. The patient is encouraged to discuss feelings and fears related to complications; the nurse meanwhile provides appropriate information regarding diabetic complications.

Teaching Patients to Self-Administer Insulin

Insulin injections are administered into the subcutaneous tissue with the use of special insulin syringes. A variety of syringes and injection-aid devices are available. Chart 41-7 provides important information to include and evaluate when teaching patients about insulin. Basic information includes explanation of the equipment, insulins, syringes, and mixing insulin.

STORING INSULIN

Cloudy insulins should be thoroughly mixed by gently inverting the vial or rolling it between the hands before drawing the solution into a syringe or a pen. Whether insulin is the short- or long-acting preparation, the vials not in use should be refrigerated and extremes of temperature should be avoided; insulin should not be allowed to freeze and should not be kept in direct sunlight or in a hot car. The insulin vial in use should be kept at room temperature to reduce local irritation at the injection site, which may occur when cold insulin is injected. If a vial of insulin will be used up in 1 month, it may be kept at room temperature. Patients should be instructed to always have a spare vial of the type or types of insulin they use (ADA, Insulin Administration, 2003). Spare vials should be refrigerated. Insulin bottles should also be inspected for flocculation, which is a frosted, whitish coating inside the bottle of intermediate- or long-acting insulins. This occurs most commonly with human insulins that are not refrigerated. If a frosted, adherent coating is present, some of the insulin is bound and should not be used.

SELECTING SYRINGES

Syringes must be matched with the insulin concentration (eg, U-100). Currently, three sizes of U-100 insulin syringes are available:

1-mL (cc) syringes that hold 100 units

 0.5-mL syringes that hold 50 units

0.3-mL syringes that hold 30 units

The concentration of insulin used in the United States is U-100; that is, there are 100 units per milliliter (or cubic centimeter). Syringe size varies. Small syringes allow patients who require small amounts of insulin to measure and draw up the amount of insulin accurately. Patients who require large amounts of insulin would use larger syringes. Although there is a U-500 (500 units/mL) concentration of insulin available by special order for patients who have severe insulin resistance and require massive doses of insulin, it is rarely used. (Individuals who travel outside of the United States should be aware that insulin is available in 40-U concentration to avoid dosing errors.) Most insulin syringes have a disposable 27- to 29-gauge needle that is approximately 0.5 inch long. The smaller syringes are marked in 1-unit increments and may be easier to use for patients with visual deficits or patients taking very small doses of insulin. The 1-mL syringes are marked in 2-unit increments. A small disposable insulin needle (29- to 30-gauge, 8 mm long) is available for very thin patients and children.

PREPARING THE INJECTION: MIXING INSULINS

When rapid- or short-acting insulins are to be given simultaneously with longer-acting insulins, they are usually mixed together in the same syringe; the longer-acting insulins must be mixed thoroughly before use. There is some question as to whether the two insulins are stable if the mixture is kept in the syringe for more than 5 to 15 minutes. This may depend on the ratio of the insulins as well as the time between mixing and injecting. When regular insulin is mixed with long-acting insulin, there is a binding reaction that slows the action of the regular insulin. This may also occur to a greater degree when mixing regular insulin with one of the Lente insulins. Patients are advised to consult their health care provider for advice on this matter. The most important issue is that patients be consistent in how they prepare their insulin injections from day to day. While there are varying opinions regarding which type of insulin (short- or longer-acting) should be drawn up into the syringe first when they are going to be mixed, the ADA recommends that the regular insulin be drawn up first. The most important issues are, again, that patients be consistent in technique so as not to draw up the wrong dose accidentally or the wrong type of insulin, and that patients not inject one type of insulin into the bottle containing a different type of insulin (ADA, Insulin Administration, 2003). For patients who have difficulty mixing insulins, two options are available: they may use a premixed insulin, or they may have prefilled syringes prepared. Premixed insulins are available in several different ratios of NPH insulin to regular insulin. The ratio of 70/30 (70% NPH and 30% regular insulin in one bottle) is the most common and is available as Novolin 70/30 (Novo Nordisk) and Humulin 70/30 (Lilly). Other ratios available include 80/20, 60/40, and 50/50. The ratio of 75% NPL and 25% insulin lispro is also available (ADA, Insulin Administration, 2002). NPL is used only to mix with Humalog; its action is the same as NPH. The appropriate initial dosage of premixed insulin must be calculated so that the ratio of NPH to regular insulin most closely approximates the separate doses needed. For patients who can inject insulin but who have difficulty drawing up a single or mixed dose, syringes can be prefilled with the help of home care nurses or family and friends. A 3-week sup- ply of insulin syringes may be prepared and kept in the refrigerator. The prefilled syringes should be stored with the needle in an upright position to avoid clogging of the needle (ADA, Insulin Administration, 2003).

WITHDRAWING INSULIN

Most (if not all) of the printed materials available on insulin dose preparation instruct patients to inject air into the bottle of insulin equivalent to the number of units of insulin to be withdrawn. The rationale for this is to prevent the formation of a vacuum inside the bottle, which would make it difficult to withdraw the proper amount of insulin. Some nurses who specialize in diabetes report that some patients (who have been taking insulin for many years) have stopped injecting air before withdrawing the insulin. These patients found that the extra step was not necessary for accurately drawing up the insulin dose. Most patients find it easier to withdraw the insulin by eliminating the step and report no difficulty in preparing the proper insulin dose. Eliminating this step (or alternating it by, for instance, injecting a syringe full of air into the vial once per week) facilitates the teaching process for some patients learning to draw up insulin for the first time. Some patients become confused with the sequence of steps involved in injecting air into two separate bottles in two different amounts before drawing up a mixed dose. For many individuals, including elderly ones, simplifying the procedure for preparing insulin injections may help them maintain independence in daily living. As with other variations in insulin injection technique, the most important factors are that the patient maintain consistency in the procedure and that the nurse be flexible when teaching new patients or assessing the skills of experienced patients.

SELECTING AND ROTATING THE INJECTION SITE

The four main areas for injection are the abdomen, arms (posterior surface), thighs (anterior surface), and hips (Fig. 41-7). Insulin is absorbed faster in some areas of the body than others. The speed of absorption is greatest in the abdomen and decreases progressively in the arm, thigh, and hip. Systematic rotation of injection sites within an anatomic area is recommended to prevent localized changes in fatty tissue (lipodystrophy). In addition, to promote consistency in insulin absorption, patients should be encouraged to use all available injection sites within one area rather than randomly rotating sites from area to area (ADA, Insulin Administration, 2002). For example, some patients almost exclusively use the abdominal area, administering each injection 0.5 to 1 inch away from the previous injection. Another approach to rotation is always to use the same area at the same time of day. For example, patients may inject morning doses into the abdomen and evening doses into the arms or legs. A few general principles apply to all rotation patterns. First, patients should try not to use the same site more than once in 2 to 3 weeks. In addition, if the patient is planning to exercise, insulin should not be injected into the limb that will be exercised, because it will be absorbed faster, and this may result in hypoglycemia. In the past, patients were taught to rotate injections from one area to the next (eg, injecting once in the right arm, then once in the right abdomen, then once in the right thigh). Patients who still use this system must be taught to avoid repeated injections into the same site within an area. However, as previously stated, it is preferable for the patient to use the same anatomic area at the same time of day consistently; this reduces dayto- day variation in blood glucose levels because of different absorption rates.

PREPARING THE SKIN

Use of alcohol to cleanse the skin is not recommended, but patients who have learned this technique often continue to use it. They should be cautioned to allow the skin to dry after cleansing with alcohol. If the skin is not allowed to dry before the injection, the alcohol may be carried into the tissues, resulting in a localized reddened area.

INSERTING THE NEEDLE

There are varying approaches to inserting the needle for insulin injections. The correct technique is based on the need for the insulin to be injected into the subcutaneous tissue. Injection that is too deep (eg, intramuscular) or too shallow may affect the rate of absorption of the insulin. Aspiration (inserting the needle and then pulling back on the plunger to assess for blood being drawn into the syringe) is generally not recommended with self-injection of insulin. Many patients who have been using insulin for an extended period have eliminated this step from their insulin injection routine with no apparent adverse effects.

PROMOTING HOME AND COMMUNITY-BASED CARE

Teaching Patients Self-Care.

Adherence to the therapeutic plan is the most important goal of self-care the patient must master. Patients who are having difficulty adhering to the diabetes treatment plan must be approached with care and understanding. Using scare tactics (such as threats of blindness or amputation if the patient does not adhere to the treatment plan) or making the patient feel guilty is not productive and may interfere with establishing a trusting relationship with the patient. Judgmental actions, such as asking the patient if he or she has “cheated” on the diet, only promote feelings of guilt and low self-esteem. If problems exist with glucose control or with the development of preventable complications, it is important to distinguish among nonadherence, knowledge deficit, and self-care deficit. It should not be assumed that problems with diabetes management are related to nonadherence. The patient may simply have forgotten or never learned certain information. The problem may be correctable simply through providing complete information and ensuring that the patient comprehends the information. Chart 41-8 details how to evaluate the effectiveness of self-injection of insulin. If knowledge deficit is not the problem, certain physical or emotional factors may be impairing the patient’s ability to perform self-care skills. For example, decreased visual acuity may impair the patient’s ability to administer insulin accurately, measure the blood glucose level, or inspect the skin and feet. In addition, decreased joint mobility (especially in the elderly) impairs the ability to inspect the bottom of the feet. Emotional factors such as denial of the diagnosis or depression may impair the patient’s ability to carry out multiple daily self-care measures. In other circumstances, family, personal, or work problems may be of higher priority to the patient. The patient facing competing demands for time and attention may benefit from assistance in establishing priorities. It is also important to assess the patient for infection or emotional stress that may lead to elevated blood glucose levels despite adherence to the treatment regimen. The following approaches by the nurse are helpful for promoting self-care management skills: Address any underlying factors (eg, knowledge deficit, selfcare deficit, illness) that may affect diabetic control. Simplify the treatment regimen if it is too difficult for the patient to follow. Adjust the treatment regimen to meet patient requests (eg, adjust diet or insulin schedule to allow increased flexibility in meal content or timing). Establish a specific plan or contract with the patient with simple, measurable goals. Provide positive reinforcement of self-care behaviors performed instead of focusing on behaviors that were neglected (eg, positively reinforce blood glucose tests that were performed instead of focusing on the number of missed tests). Help the patient to identify personal motivating factors rather than focusing on wanting to please the doctor or nurse. Encourage the patient to pursue life goals and interests; discourage an undue focus on diabetes.

Continuing Care.

As discussed, continuing care of the patient with diabetes is critical in managing and preventing complications. The degree to which the client interacts with health care providers to obtain ongoing care depends on many factors. Age, socioeconomic level, existing complications, type of diabetes, and comorbid conditions all may dictate the frequency of follow-up visits. Many patients with diabetes may be seen by home health nurses for diabetic education, wound care, insulin preparation, or assistance with glucose monitoring. Even patients who achieve excellent glucose control and have no complications can expect to see their primary health care provider at least twice a year for ongoing evaluation. In addition to follow-up care with health professionals, participation in support groups is encouraged for those who have had diabetes for many years as well as those who are newly diagnosed. Such participation may assist the patient and family in coping with changes in lifestyle that occur with the onset of diabetes and with its complications. Those who participate in support groups often have an opportunity to share valuable information and experiences and to learn from others. Support groups provide an opportunity for discussion of strategies to deal with diabetes and its management and to clarify and verify information with the nurse or other health care professionals. Participation in support groups may help patients and their families to become more knowledgeable about diabetes and its management and may promote adherence to the management plan. Another very important role of the nurse is to remind the patient about the importance of participating in other health promotion activities and recommended health screening.

Acute Complications of Diabetes

There are three major acute complications of diabetes related to short-term imbalances in blood glucose levels: hypoglycemia, DKA, and HHNS, which is also called hyperglycemic hyperosmolar nonketotic coma or hyperglycemic hyperosmolar syndrome.

HYPOGLYCEMIA (INSULIN REACTIONS)

Hypoglycemia (abnormally low blood glucose level) occurs when the blood glucose falls to less than 50 to 60 mg/dL (2.7 to 3.3 mmol/L). It can be caused by too much insulin or oral hypoglycemic agents, too little food, or excessive physical activity. Hypoglycemia may occur at any time of the day or night. It often occurs before meals, especially if meals are delayed or snacks are omitted. For example, midmorning hypoglycemia may occur when the morning regular insulin is peaking, whereas hypoglycemia that occurs in the late afternoon coincides with the peak of the morning NPH or Lente insulin. Middle-of-the-night hypoglycemia may occur because of peaking evening or predinner NPH or Lente insulins, especially in patients who have not eaten a bedtime snack.

Clinical Manifestations

The clinical manifestations of hypoglycemia may be grouped into two categories: adrenergic symptoms and central nervous system (CNS) symptoms. In mild hypoglycemia, as the blood glucose level falls, the sympathetic nervous system is stimulated, resulting in a surge of epinephrine and norepinephrine. This causes symptoms such as sweating, tremor, tachycardia, palpitation, nervousness, and hunger. In moderate hypoglycemia, the fall in blood glucose level deprives the brain cells of needed fuel for functioning. Signs of impaired function of the CNS may include inability to concentrate, headache, lightheadedness, confusion, memory lapses, numbness of the lips and tongue, slurred speech, impaired coordination, emotional changes, irrational or combative behavior, double vision, and drowsiness. Any combination of these symptoms (in addition to adrenergic symptoms) may occur with moderate hypoglycemia. In severe hypoglycemia, CNS function is so impaired that the patient needs the assistance of another person for treatment of hypoglycemia. Symptoms may include disoriented behavior, seizures, difficulty arousing from sleep, or loss of consciousness

Assessment and Diagnostic Findings

Hypoglycemic symptoms can occur suddenly and unexpectedly. The combination of symptoms varies considerably from person to person. To some degree, this may be related to the actual level to which the blood glucose drops or to the rate at which it is dropping. For example, patients who usually have a blood glucose level in the hyperglycemic range (eg, in the 200s or greater) may feel hypoglycemic (adrenergic) symptoms when their blood glucose quickly drops to 120 mg/dL (6.6 mmol/L) or less. Conversely, patients who frequently have a glucose level in the low range of normal may be asymptomatic when the blood glucose slowly falls to less than 50 mg/dL (2.7 mmol/L). Another factor contributing to altered hypoglycemic symptoms is a decreased hormonal (adrenergic) response to hypoglycemia. This occurs in some patients who have had diabetes for many years. It may be related to one of the chronic diabetic complications, autonomic neuropathy (see the section in this chapter on hypoglycemic unawareness). As the blood glucose level falls, the normal surge in adrenalin does not occur. The patient does not feel the usual adrenergic symptoms, such as sweating and shakiness. The hypoglycemia may not be detected until moderate or severe CNS impairment occurs. These patients must perform SMBG on a frequent regular basis, especially before driving or engaging in other potentially dangerous activities.

Gerontologic Considerations

In the elderly diabetic patient, hypoglycemia is a particular concern for many reasons:

Elderly people frequently live alone and may not recognize the symptoms of hypoglycemia.

With decreasing renal function, it takes longer for oral hypoglycemic agents to be excreted by the kidneys.

Skipping meals may occur because of decreased appetite or financial limitations.

 Decreased visual acuity may lead to errors in insulin administration.

Management

 Immediate treatment must be given when hypoglycemia occurs. The usual recommendation is for 15 g of a fast-acting concentrated source of carbohydrate such as the following, given orally:

Three or four commercially prepared glucose tablets

4 to 6 oz of fruit juice or regular soda

6 to 10 Life Savers or other hard candies

2 to 3 teaspoons of sugar or honey

 It is not necessary to add sugar to juice, even if it is labeled as unsweetened juice: the fruit sugar in juice contains enough carbohydrate to raise the blood glucose level. Adding table sugar to juice may cause a sharp increase in the blood glucose level, and the patient may experience hyperglycemia for hours after treatment. The blood glucose level should be retested in 15 minutes and retreated if it is less than 70 to 75 mg/dL (3.8 to 4 mmol/L). If the symptoms persist more than 10 to 15 minutes after initial treatment, the treatment is repeated even if blood glucose testing is not possible. Once the symptoms resolve, a snack containing protein and starch (eg, milk or cheese and crackers) is recommended unless the patient plans to eat a regular meal or snack within 30 to 60 minutes.

TEACHING PATIENTS

It is important for patients with diabetes, especially those receiving insulin, to learn that they must carry some form of simple sugar with them at all times (ADA, Insulin Administration, 2002). There are many different commercially prepared glucose tablets and gels that patients may find convenient to carry. If the patient has a hypoglycemic reaction and does not have any of the recommended emergency foods available, any available food (preferably a carbohydrate food) should be eaten. Patients are advised to refrain from eating high-calorie, highfat dessert foods (eg, cookies, cakes, doughnuts, ice cream) to treat hypoglycemia. The high fat content of these foods may slow the absorption of the glucose, and the hypoglycemic symptoms may not resolve as quickly as they would with the intake of carbohydrates. The patient may subsequently eat more of the foods when symptoms do not resolve rapidly. This in turn may cause very high blood glucose levels for several hours after the reaction and may also contribute to weight gain. Patients who feel unduly restricted by their meal plan may view hypoglycemic episodes as a time to reward themselves with desserts. It may be more prudent to teach these patients to incorporate occasional desserts into the meal plan. This may make it easier for them to limit their treatment of hypoglycemic episodes to simple (low-calorie) carbohydrates such as juice or glucose tablets.

INITIATING EMERGENCY MEASURES

For patients who are unconscious and cannot swallow, an injection of glucagon 1 mg can be administered either subcutaneously or intramuscularly. Glucagon is a hormone produced by the alpha cells of the pancreas that stimulates the liver to release glucose (through the breakdown of glycogen, the stored glucose). Injectable glucagon is packaged as a powder in 1-mg vials and must be mixed with a diluent before being injected. After injection of glucagon, it may take up to 20 minutes for the patient to regain consciousness. A concentrated source of carbohydrate followed by a snack should be given to the patient on awakening to pre vent recurrence of hypoglycemia (because the duration of the action of 1 mg of glucagon is brief [its onset is 8 to 10 minutes and its action lasts 12 to 27 minutes]) and to replenish liver stores of glucose. Some patients experience nausea after the administration of glucagon; if this occurs, the patient should be turned to the side to prevent aspiration. The patient should be instructed to notify the physician after severe hypoglycemia has occurred. Glucagon is sold by prescription only and should be part of the emergency supplies kept available by patients with diabetes who require insulin. Family members, neighbors, or coworkers should be instructed in the use of glucagon. This is especially true for patients who receive little or no warning of hypoglycemic episodes. In the hospital or emergency department, patients who are unconscious or cannot swallow may be treated with 25 to 50 mL 50% dextrose in water (D50W) administered intravenously. The effect is usually seen within minutes. Patients may complain of a headache and of pain at the injection site. Assuring patency of the intravenous (IV) line used for injection of 50% dextrose is essential because hypertonic solutions such as 50% dextrose are very irritating to the vein.

PROMOTING HOME AND COMMUNITY-BASED CARE

Teaching Patients Self-Care.

Hypoglycemia is prevented by a consistent pattern of eating, administering insulin, and exercising. Between-meal and bedtime snacks may be needed to counteract the maximum insulin effect. In general, the patient should cover the time of peak activity of insulin by eating a snack and by taking additional food when physical activity is increased. Routine blood glucose tests are performed so that changing insulin requirements may be anticipated and the dosage adjusted. Because unexpected hypoglycemia may occur, all patients treated with insulin should wear an identification bracelet or tag stating that they have diabetes. Patients and family members must be instructed about the symptoms of hypoglycemia. Family members in particular must be made aware that any subtle (but unusual) change in behavior may be an indication of hypoglycemia. They should be taught to encourage and even insist that the person with diabetes assess blood glucose levels if hypoglycemia is suspected. Some patients (when hypoglycemic) become very resistant to testing or eating and become angry at family members trying to treat the hypoglycemia. Family members must be taught to persevere and to understand that the hypoglycemia can cause irrational behavior. Some patients with autonomic neuropathy or those taking beta blockers such as propranolol to treat hypertension or cardiac dysrhythmias may not experience the typical symptoms of hypoglycemia. It is very important for these patients to perform blood glucose tests on a frequent and regular basis. Patients who have type 2 diabetes and who take oral sulfonylurea agents may also develop hypoglycemia (especially those taking chlorpropamide, a long-lasting oral hypoglycemic agent).

DIABETIC KETOACIDOSIS

DKA is caused by an absence or markedly inadequate amount of insulin. This deficit in available insulin results in disorders in the metabolism of carbohydrate, protein, and fat. The three main clinical features of DKA are: Hyperglycemia Dehydration and electrolyte loss Acidosis

Pathophysiology

Without insulin, the amount of glucose entering the cells is reduced and the liver increases glucose production. Both factors lead to hyperglycemia. In an attempt to rid the body of the excess glucose, the kidneys excrete the glucose along with water and electrolytes (eg, sodium and potassium). This osmotic diuresis, which is characterized by excessive urination (polyuria), leads to dehydration and marked electrolyte loss. Patients with severe DKA may lose up to 6.5 liters of water and up to 400 to 500 mEq each of sodium, potassium, and chloride over a 24-hour period. Another effect of insulin deficiency or deficit is the breakdown of fat (lipolysis) into free fatty acids and glycerol. The free fatty acids are converted into ketone bodies by the liver. In DKA there is excessive production of ketone bodies because of the lack of insulin that would normally prevent this from occurring. Ketone bodies are acids; their accumulation in the circulation leads to metabolic acidosis. Three main causes of DKA are decreased or missed dose of insulin, illness or infection, and undiagnosed and untreated diabetes (DKA may be the initial manifestation of diabetes). An insulin deficit may result from an insufficient dosage of insulin prescribed or from insufficient insulin being administered by the patient. Errors in insulin dosage may be made by patients who are ill and who assume that if they are eating less or if they are vomiting, they must decrease their insulin doses. (Because illness, especially infections, may cause increased blood glucose levels, patients do not need to decrease their insulin doses to compensate for decreased food intake when ill and may even need to increase the insulin dose.) Other potential causes of decreased insulin include patient error in drawing up or injecting insulin (especially in patients with visual impairments), intentional skipping of insulin doses (especially in adolescents with diabetes who are having difficulty coping with diabetes or other aspects of their lives), or equipment problems (eg, occlusion of insulin pump tubing). Illness and infections are associated with insulin resistance. In response to physical (and emotional) stressors, there is an increase in the level of “stress” hormones—glucagon, epinephrine, norepinephrine, cortisol, and growth hormone. These hormones promote glucose production by the liver and interfere with glucose utilization by muscle and fat tissue, counteracting the effect of insulin. If insulin levels are not increased during times of illness and infection, hyperglycemia may progress to DKA (Quinn, 2001c).

Clinical Manifestations

The signs and symptoms of DKA are listed in Figure 41-8. The hyperglycemia of DKA leads to polyuria and polydipsia (increased thirst). In addition, patients may experience blurred vision, weakness, and headache. Patients with marked intravascular volume depletion may have orthostatic hypotension (drop in systolic blood pressure of 20 mm Hg or more on standing). Volume depletion may also lead to frank hypotension with a weak, rapid pulse. The ketosis and acidosis of DKA lead to GI symptoms such as anorexia, nausea, vomiting, and abdominal pain. The abdominal pain and physical findings on examination can be so severe that they resemble an acute abdominal disorder that requires surgery. Patients may have acetone breath (a fruity odor), which occurs with elevated ketone levels. In addition, hyperventilation (with very deep, but not labored, respirations) may occur. These Kussmaul respirations represent the body’s attempt to decrease the acidosis, counteracting the effect of the ketone buildup. In addition, mental status changes in DKA vary widely from patient to patient. Patients may be alert, lethargic, or comatose, most likely depending on the plasma osmolarity (concentration of osmotically active particles).

Assessment and Diagnostic Findings

Blood glucose levels may vary from 300 to 800 mg/dL (16.6 to 44.4 mmol/L). Some patients have lower glucose values, and others have values of 1,000 mg/dL (55.5 mmol/L) or more (usually depending on the degree of dehydration). The severity of DKA is not necessarily related to the blood glucose level. Some patients may have severe acidosis with modestly elevated blood glucose levels, whereas others may have no evidence of DKA despite blood glucose levels of 400 to 500 mg/dL (22.2 to 27.7 mmol/L) (Quinn, 2001c). Evidence of ketoacidosis is reflected in low serum bicarbonate (0 to 15 mEq/L) and low pH (6.8 to 7.3) values. A low PCO2 level (10 to 30 mm Hg) reflects respiratory compensation (Kussmaul respirations) for the metabolic acidosis. Accumulation of ketone bodies (which precipitates the acidosis) is reflected in blood and urine ketone measurements. Sodium and potassium levels may be low, normal, or high, depending on the amount of water loss (dehydration). Despite the plasma concentration, there has been a marked total body depletion of these (and other) electrolytes. Ultimately, these electrolytes will need to be replaced. Elevated levels of creatinine, blood urea nitrogen (BUN), hemoglobin, and hematocrit may also be seen with dehydration. After rehydration, continued elevation in the serum creatinine and BUN levels will be present in the patient with underlying renal insufficiency.

Prevention

For prevention of DKA related to illness, patients must be taught “sick day” rules for managing their diabetes when ill (Chart 41-9). The most important issue to teach patients is not to eliminate insulin doses when nausea and vomiting occur. Rather, they should take their usual insulin dose (or previously prescribed special “sick day” doses) and then attempt to consume frequent small portions of carbohydrates (including foods usually avoided, such as juices, regular sodas, and gelatin). Drinking fluids every hour is important to prevent dehydration. Blood glucose and urine ketones must be assessed every 3 to 4 hours. If the patient cannot take fluids without vomiting, or if elevated glucose or ketone levels persist, the physician must be contacted. Patients are taught to have available foods for use on sick days. In addition, a supply of urine test strips (for ketone testing) and blood glucose test strips should be available. Patients must know how to contact their physician 24 hours a day. Diabetes self-management skills (including insulin administration and blood glucose testing) should be assessed to ensure that an error in insulin administration or blood glucose testing did not occur. Psychological counseling is recommended for patients and family members if an intentional alteration in insulin dosing was the cause of the DKA.

Medical Management

In addition to treating hyperglycemia, management of DKA is aimed at correcting dehydration, electrolyte loss, and acidosis (Quinn, 2001c).

REHYDRATION

In dehydrated patients, rehydration is important for maintaining tissue perfusion. In addition, fluid replacement enhances the excretion of excessive glucose by the kidneys. Patients may need up to 6 to 10 liters of IV fluid to replace fluid losses caused by polyuria, hyperventilation, diarrhea, and vomiting. Initially, 0.9% sodium chloride (normal saline) solution is administered at a rapid rate, usually 0.5 to 1 L per hour for 2 to 3 hours. Half-strength normal saline (0.45%) solution (also known as hypotonic saline solution) may be used for patients with hypertension or hypernatremia or those at risk for heart failure. After the first few hours, half-normal saline solution is the fluid of choice for continued rehydration, if the blood pressure is stable and the sodium level is not low. Moderate to high rates of infusion (200 to 500 mL per hour) may continue for several more hours. When the blood glucose level reaches 300 mg/dL (16.6 mmol/L) or less, the IV fluid may be changed to dextrose 5% in water (D5W) to prevent a precipitous decline in the blood glucose level (ADA, Hyperglycemic Crisis in Patients with Diabetes Mellitus, 2003). Monitoring fluid volume status involves frequent measurements of vital signs (including monitoring for orthostatic changes in blood pressure and heart rate), lung assessment, and monitoring intake and output. Initial urine output will lag behind IV fluid intake as dehydration is corrected. Plasma expanders may be necessary to correct severe hypotension that does not respond to IV fluid treatment. Monitoring for signs of fluid overload is especially important for older patients, those with renal impairment, or those at risk for heart failure.

RESTORING ELECTROLYTES

The major electrolyte of concern during treatment of DKA is potassium. Although the initial plasma concentration of potassium may be low, normal, or even high, there is a major loss of potassium from body stores and an intracellular to extracellular shift of potassium. Further, the serum level of potassium drops during the course of treatment of DKA as potassium re-enters the cells; therefore, it must be monitored frequently. Some of the factors related to treating DKA that reduce the serum potassium concentration include: Rehydration, which leads to increased plasma volume and subsequent decreases in the concentration of serum potassium. Rehydration also leads to increased urinary excretion of potassium. Insulin administration, which enhances the movement of potassium from the extracellular fluid into the cells. Cautious but timely potassium replacement is vital to avoid dysrhythmias that may occur with hypokalemia. Up to 40 mEq per hour may be needed for several hours. Because extracellular potassium levels drop during DKA treatment, potassium must be infused even if the plasma potassium level is normal.

Frequent (every 2 to 4 hours initially) electrocardiograms and laboratory measurements of potassium are necessary during the first 8 hours of treatment. Potassium replacement is withheld only if hyperkalemia is present or if the patient is not urinating.