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 in-take 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 management of diabetes is so complex, a registered dietitian who un-derstands 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 Com-mittee 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 inter-vals 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 dia-betes), 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).. Obesity is associated with an increased resistance to in-sulin; 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 lev-els. 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 chal-lenging 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.
For all patients with diabetes, the meal plan must consider the pa-tient’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 con-trast to the older concept of maintaining a constant dose of in-sulin 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 edu-cation addresses the importance of consistent eating habits, the relationship of food and insulin, and the provision of an individ-ualized 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 di-abetes or feelings of deprivation and undue restriction in eating. In any case, it helps to emphasize that using the exchange sys-tem (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 ac-tivities and information.
Calorie-controlled diets are planned by first calculating the indi-vidual’s energy needs and caloric requirements based on the pa-tient’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, calorie-controlled diets are often confusing and difficult to comply with. They require patients to measure precise portions and to eat spe-cific 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 as-sess 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.
A diabetic meal plan also focuses on the percentage of calories to come from carbohydrates, proteins, and fats. In general, carbohy-drate 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 inconsis-tent with the goal of reducing the cardiovascular disease com-monly associated with diabetes (ADA, Evidence-Based Nutrition Principles and Recommendations for the Treatment and Preven-tion of Diabetes and Related Complications, 2003).
The caloric distribution currently recommendedis higher in carbohydrates than in fat and protein. However, re-search into the appropriateness of a higher-carbohydrate diet in patients with decreased glucose tolerance is ongoing, and recom-mendations 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 un-derstand than the diabetic food exchange list, and allows more ac-curate 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 count-ing carbohydrates alone, protein will be factored into the calcu-lations. This is especially true if the meal consists of only meat, fish, and non-starchy vegetables.
An alternative to counting grams of carbohydrate is measur-ing servings or choices. This method is used more often by peo-ple 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.
The recommendations regarding fat content of the diabeticdiet 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 rec-ommendations include limiting the total intake of dietary choles-terol to less than 300 mg/day. This approach may help to reduce risk factors such as elevated serum cholesterol levels, which are as-sociated with the development of coronary artery disease, the lead-ing 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 in-take may be reduced in patients with early signs of renal disease.
The use of fiber in diabetic diets has received increasedattention as researchers study the effects on diabetes of a high-carbohydrate, high-fiber diet. This type of diet plays a role in low-ering 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 Diag-nosis 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 ab-sorption 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 in-crease 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 pre-vent 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.
To teach diet principles and to help patients in meal planning, several systems have been developed in which foods are orga-nized 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.
A commonly used tool for nutritional manage-ment 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 approxi-mately 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, allow-ing 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 inter-changeable 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 man-ufacturers and restaurants publish exchange lists that describe their products as well. For more nutrition information, contact the ADA.
The Food Guide Pyramid is anothertool 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 pyra-mid 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 ob-tain 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 pa-tients learning how to control food portions and how to identify which foods contain carbohydrate, protein, and fat.
One of the main goals of diet therapy in dia-betes 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 ques-tioned (ADA, Expert Committee on the Diagnosis and Classifi-cation 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, puréed, 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 mon-itoring of blood glucose levels can use this information to adjust their insulin doses for variations in food intake.
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 peo-ple without diabetes should be applied to patients with diabetes. Moderation is recommended. The main danger of alcohol con-sumption by a diabetic patient is hypoglycemia, especially for pa-tients who take insulin. Alcohol may decrease the normal physiologic reactions in the body that produce glucose (gluconeo-genesis). Thus, if a diabetic patient takes alcohol on an empty stom-ach, there is an increased likelihood that hypoglycemia will develop. In addition, excessive alcohol intake may impair the pa-tient’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 in-volves facial flushing, warmth, headache, nausea, vomiting, sweat-ing, 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.
Using sweeteners is acceptable for patients with diabetes, espe-cially if it assists in overall dietary adherence. Moderation in the amount of sweetener used is encouraged to avoid potential ad-verse 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 lax-ative 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 sweet-ener 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, frost-ings, and frozen dairy products.
Foods labeled “sugarless” or “sugar-free” may still provide calo-ries 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 carbohy-drates such as honey, brown sugar, and corn syrup. In addition, these supposedly healthy snacks frequently contain saturated veg-etable fats (eg, coconut or palm oil), hydrogenated vegetable fats, or animal fats, which may be contraindicated in patients with elevated blood lipid levels.