Symposium on Diabetes Mellitus
Current Principles of Dietary Therapy of Diabetes Mellitus Ronald A. Arky, M.D. *
Two major reports concerned with diabetes mellitus published during the last several years emphasize the important role of diet in the management of this disorder. In 1971, the University Group Diabetes Program (UGDP) reported results of the first phase of a multicenter study, and concluded that "diet alone" may be more effective in prolonging the life of the diabetic than other therapeutic agents. 29 While controversy still stirs about this report, no one disputes the conclusions concerned with diet. In 1975, the National Commission on Diabetes recognized the marked increase in the prevalence of diabetes mellitus among Americans during the 8 year period 1965 through 1973. 24 In addition, the Commission noted that the chance for diabetes mellitus doubles for every 20 per cent of excessive weight. Hence, the strong implication that "diet" may play a role in the pathogenesis of diabetes. These documents, textbooks, and other instructional materials refer to "diet" as a therapeutic agent for the diabetic without elaborating specifics. The generic term "diet therapy" has multiple implications. For many, "diet therapy" is a concept based upon tradition and folklore since the quality and quantity of applicable investigative data are slim. This review examines current concepts of diet therapy and the principles on which these are based, and attempts to elaborate diet therapy in the context of the pathogenesis of the disease.
Diabetes Mellitus: Heterogeneity of the Syndrome Ideally, before therapy for a disorder is defined, some understanding of the pathogenesis of that disorder should be appreciated in order to determine the "site of action'" of the therapy. Diabetes mellitus is a heterogeneous syndrome with two basic etiologic lesions: one involves a disordered beta cell and is characterized by insulin deficiency; the other involves a resistance to the effectiveness of insulin on peripheral tissue as muscle, liver, and adipose tissue and is characterized by "Professor of Medicine, Harvard Medical School at the Mount Auburn Hospital; Chief of Medicine, Mount Auburn Hospital, Cambridge, Massachusetts
Medical Clinics of North America- Vol. 62, No. 4, July 1978
655
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RONALD A. ARKY
normal or even elevated quantities of circulating insulin. Both major defects may be present in some diabetics. Patients with t~e first .lesion are "insulin-dependent" or "ketone-p~one". diab~tics. PatIent~, wIth the second or more common lesion are non-msuhn dependent and are frequently overweight. . Studies with monozygous twins confirm that from a genetIc standpoint there are also two types of ~iabetes.lH. 28 Interestingly en~ugh, ~he "insulin-dependent" variety of dIabetes appears to be a mamfestatIOn of both genetic and environmental factors. The non-insulin dependent form of diabetes on the other hand seems to be predominantly a genetic lesion for when it appears in one member of a pair of monozygic twins the other is always affected within a very short period of time.!7,!~ In addition to the twin studies, data concerned with the HLA system indicate that in insulin-dependent diabetics certain antigens in both the Band D locus are more prevalent and may serve as markers for potential diabetes.!3,27 Whether the presence of these HLA antigens predisposes individuals for specific infections remains speculative.
General Principles of Diet Therapy The primary objective in the dietary treatment of diabetes mellitus concerns the control of caloric intake! Youngsters with diabetes mellitus must receive sufficient numbers of calories to assure normal growth. Patients with the "non-insulin dependent" variety of diabetes tend to be overweight and frequently require hypocaloric diets. At initial contact, the physician must calculate the patient's ideal body weight. Table 1 gives a simplified system to approximate this value. Once the desired weight has been estimated, the caloric needs of the patient should be determined. This calculation depends upon the activity of the patient and whether or not weight loss or weight gain is deemed desirable. To determine an individual's basal caloric needs, multiply the "desired weight" by 10 (e.g., 120 x 10 = 1200 kilocalories). If the individual leads a sedentary life, add to this value the product of the desired body weight times 3; if the individual is moderately active add the desired body weight times 5; and if the individual pursues very strenuous activities, then add the desired body weight times 10. For overweight individuals, reducing the daily intake by 750 to 1000 kilocalories below the calculated requirements will induce a weight loss of 2 to 21f2 pounds per week. Pregnant or lactating women need 300 to 500 extra kilocalories per day to provide for normal fetal growth or milk production. Table L BUILD
Medium Frame Small Frame Large Frame
Estimating Desirable Body Weight! WOMEN
100 lb for first 5 ft of height, plus 5 lb for each additional inch Subtract 10 per cent Add 10 per cent
MEN
106 for the first 5 ft of height, plus 6 lb for each additional inch Subtract 10 per cent Add 10 per cent
DIETARY THERAPY
657
The second basic principle of dietary treatment is education. Most successful educational programs employ the team approach, where each member of the team (physician-dietitian-nurse) appreciates the importance of diet therapy and presents a unified approach. When the assistance of a dietary counsellor is unavailable, the physician must assume prime reponsibility and provide the diet prescription. Diet education is a constant process. Single encounters between the diet counsellor and the patient are useless. On each visit, the physician must emphasize the importance of caloric intake and evaluate the patient's compliance. Dietary instruction should never proceed unless the counsellor (physician-dietitian or nurse) assesses the patient's capability to comprehend the basic principles of diet management. In addition, the patient must acknowledge his/her responsibility for the success of this form of therapy. Some physicians advise setting up a "contract" before embarking upon an educational program. The third principle relates the integration of diet therapy with the other therapeutic modalities used by the diabetic. Activity and exercise are essential for all diabetics. Training facilitates the action of endogenous insulin. Insulin-dependent diabetics must coordinate their exercise activity and diet with the action of their medication. Such patien.ts require the intake of food at scheduled regular intervals and must have access to a readily available source of carbohydrate whenever participating in exercise.
SPECIFIC GUIDELINES FOR DIET THERAPY The Obese Diabetic Substantial data are available to demonstrate that weight loss in obese diabetics lowers the fasting blood sugar and improves glucose tolerance. Frequently, the loss of 7 to 10 Ib will be accompanied by marked improvement in fasting glucose levels. The precise method used to reduce weight seems irrelevant; apparently the absolute loss of weight accounts for the increase in the number of insulin receptors and the theoretical repair of intracellular metabolic effects that characterize the "insulin resistance" of obesity. Davidson has revised the teachings of Rollo and Naunyn and suggests "short term fasts" (one week) to initiate diet therapy in obese diabetics.14 Such an approach should be initiated only in patients who are: (1) under constant medical surveillance; (2) appreciate the severe complications that can result from starvation; and (3) have the ability to measure urine ketones and seek medical attention when symptomaticY Short term fasts must be followed by maintenance hypocaloric diets with the aim to achieve desired body weight. Bistrian and his colleagues advocated a protein-sparing modified fast for obese diabeticsY Such a diet, calculated to provide 1.2 or 1.4 gm of protein per kilogram of ideal body weight, is said to preserve lean body mass during weight loss. The protein-sparing modified fast not only improves diabetes but in some instances enables the patient to discon-
658
RONALD A. ARKY
tinue the use of exogenous insulin. These investigators suggest the use of a diet containing 1.3 gm of protein per kilogram of body weight daily as a maintenance measure to achieve body weight. Weight loss from whatever diet is ineffective unless the weight loss is maintained. Efforts to achieve desired body weight should be continuous and patients urged to lose 11/2 to 2 Ib per week. Unfortunately, there are no data to indicate that the improved glucose tolerance achieved by weight loss persists even if such weight loss is maintained, whether the improved glucose tolerance results in fewer anatomical complications of diabetes. Should carbohydrate be restricted in obese diabetics? Although· not universally accepted,2(; the American Diabetes Association in a policy statement maintains there is no need to restrict "disproportionately the intake of carbohydrate in the diet of most diabetic patients."5 Such a philosophy does not advocate unrestricted quantities of carbohydrate or encourage the use of "simple sugars;" however, it does recognize that diets with increased quantities of carbohydrate may result in improved glucose tolerance 7 and may not require increased quantities of insulin to control glucosuria. 2:l Total carbohydrate intake should represent 50 to 60 per cent of total energy consumption. Approximately 10 to 15 per cent of carbohydrate calories should be in the form of monosaccharides and disaccharides. Exceptions to this rule apply only to diabetics with hypertriglyceridemia that is aggravated by carbohydrate ingestion. In such individuals, carbohydrate calories should comprise 35 per cent of the total caloric input. The contention that carbohydrates, especially "refined sugars," are diabetogenic R-1O is challenged by the observation that the prevelance of diabetes in several populations around the world is "most impressive" and consistently associated with obesity and not with the intake of any specific foodstuff.:l ! Frequently, the introduction of large quantities of refined carbohydrate in a society reflects an improved economic standard in that society and is often accompanied by higher total caloric and fat intake, an increasingly sedentary pattern of life, and increased psychological stresses-all of which are diabetogenic. Several recent studies indicate that when diabetics consume meals that contain unabsorbable carbohydrates and guar gum and pectin, postprandial fluctuations in blood glucose as well as in the amount of glucosuria are reduced. 2(}-22 While further investigation is required to clarify the mechanism by which unabsorbable carbohydrates affect glucosuria and hyperglycemia, these preliminary observations indicate that high fiber diets may alleviate wide swings in blood glucose in the diabetic and reduce the need for hypoglycemic agents. Fats should comprise no more than 35 per cent of the total calories ingested by the obese diabetic. Debate continues about the preventive role of polyunsaturated fats in the pathogenesis of atherosclerosis. Prudent clinicians urge reduction in the consumption of animal fats with an eye toward weight reduction and maintaining normal plasma lipid levels. Protein calories should account for 10 to 15 per cent of the total energy intake of the adult.
DIETARY THERAPY
659
The Insulin-Dependent Diabetic Youngsters with diabetes must ingest an adequate number of calories to assure normal growth and maturation: formerly diabetic dwarfism was common among children placed on very restricted diets.l1 Diets that are nutritionally sound for non-diabetics are equally sound for diabetics. The sole limitation concerns "simple sugars" such as sucrose which may aggravate postprandial hyperglycemia. 12 While the symptoms of hyperglycemia and hypo glycemia are to be avoided, many insulin-dependent diabetics are refractory to both diet and insulin. The most important dietary concept that the insulin-requiring patient must accept pertains to the timing of meals. Dietary patterns must be tailored to fit the individual patient's activity and exercise schedule. While in the non-insulin dependent patient, food is usually divided into three meals per day, in the insulin-dependent individual, food is routinely divided into three meals and a bedtime snack and occasionally in youngsters into mid-afternoon or mid-morning snacks as well. For example, in the active youngster going to school, total calories may be divided such that 2/10's are given for breakfast, 2/10's at lunch, 1/10th as a mid-afternoon snack, 4/10's as the evening meal and the final 10th as a bedtime snack. Obviously, individualization must be the rule. Insulin-requiring patients must always have available a source of simple carbohydrate to counteract hypo glycemia. It is essential that these simple dietary concepts be presented to the insulin-requiring diabetic and his/her family immediately after the diagnosis is made. Young diabetics must appreciate the need for balanced meals eaten at regular intervals early in the course of their disease. Failure of the pediatrician or other physician to emphasize these basic principles at an early stage often results in individuals who are recalcitrant to a reasonable dietary approach and also to the general self-care measures that must be administered by the diabetic himself. Hyperlipoproteinemia in the Diabetic The relationship between diabetes and hyperlipoproteinemia has a palindromic quality: individuals with disordered lipid metabolisms have a high incidence of diabetes while, conversely, diabetics, especially those with persistent hyperglycemia, have a high incidence of hyperlipidemia.25 Often it is impossible to determine which of the two metabolic disorders has primacy. Three specific situations warrant discussion from the standpoint of dietary therapy: DECOMPENSATED DIABETES MELLITUS. This condition characterized by severe hyperglycemia and ketonemia is accompanied by elevated levels of triglycerides and cholesterol. Hypertriglyceridemia may represent an increase in both circulating chylomicrons and very low density lipoprotein (VLDL). Insulin therapy is not only necessary to stabilize carbohydrate metabolism in the uncontrolled state, but is also effective in lowering circulating triglycerides and cholesterol. Dietary therapy in the uncontrolled diabetic will be ineffective unless adequate insulin is administered. After the diabetes is stabilized, a low fat diet with less than 30 per cent of total calories as fat should be initiated.
660
RONALD A. ARKY
DIABETES, OBESITY AND HYPERTRIGLYCERIDEMIA (HYPER PRE-BETA LIPOPROTEINEMIA OR VLDL). This triad represents the most frequent clinical form of a lipid disorder observed in the diabetic population. Each component of the triad improves with weight 10ss.2.; Frequently, only a modest weight loss is required to effect significant reduction in triglyceride levels. Provided weight loss is maintained, the triglyceride levels will remain in the normal to high normal range. Some of these patients are "carbohydrate-sensitive" and in addition to a hypocaloric diet, the carbohydrate content of the diet should be reduced to 35 per cent or less of the total caloric intake. Patients with this triad should avoid alcohol. Occasionally, in spite of a hypocaloric diet, the diabetes progresses to an insulin-dependent type. In this situation, adequate insulin is required to prevent the overproduction of VLDL as well as to assure adequate amounts of tissue lipoprotein lipase and to assure adequate removal of chylomicrons. :1 DIABETES AND HYPERCHOLESTEROLEMIA (HYPER-BETA LIPOPROTEINEMIA OR HYPER-Low DENSITY LIPOPROTEINEMIA). In both the homozygous and heterozygous forms of hypercholesterolemia, diabetes may occur and usually is not severe. Such patients should receive diets that contain 300 mg or less of cholesterol per day and urged to strictly limit the ingestion of animal fats. Recently, Bennion and Grundy 4 demonstrated that in the uncontrolled diabetic, cholesterol balance and fasting plasma cholesterol are higher than when the patient's carbohydrate metabolism is stabilized with insulin. They concluded that insulin deficiency and hyperglycemia are accompanied by elevated levels of cholesterol that may play an important role in the pathogenesis of the macroangiopathy of diabetes.
Educational Issues The major issues concerning diet and diabetes are not difficult to define but are extremely difficult to relate to the practicing physician and patient. That efforts to convey the principles and ideas listed above have failed in the past is well documented.:JO Efforts to overcome the reluctance of physicians to accept principles such as hypocaloric diets and diets with higher carbohydrate content than formerly advocated may be beneficial comprise only one facet of the overall problem. More importantly, it is still uncertain how to assess patient comprehension, compliance, and continuance of dietary routine. Within the past two years, the American Diabetes Association and the American Dietetic Association have published a modification of the original Exchange List in an effort to update these lists and to provide a simplified basis for teaching patients the fundamentals about food and nutrition. 2 To aid the professional in the use of the Exchange Lists, these organizations have also developed a Professional Guide.! It is apparent that every diabetic requires instruction in dietary matters. However, a single session will not achieve the behavioral changes that are essential if results are to be expected from educational experiences. 32 Dietary counselling is an art and few physicians have the know-how or time to devote to this important therapeutic measure.
661
DIETARY THERAPY
Whenever possible, the physician should utilize the services of a diet counsellor and periodically refer the patient for follow-up teaching. Many dietitians have devised their own approach in teaching diabetics and several educators have suggested using instrumentation and audiovisual devices. Whatever the method used, some understanding of the patient's ability to comprehend and willingness to comply with instructions must be assessed. If there is one major gap in the educational processes used to teach the diabetic, the area of "diet instruction" must head the list.
SUMMARY Diabetes mellitus is a complex diathesis with two dominant pathogenic lesions: one, a failure of the islet's beta cells; the other, a resistance to the actions of insulin. Diet therapy for each patient should be designed within the framework of these pathogenic concepts. The most important objective of dietary treatment is control of total caloric intake to achieve desired body weight. Patients with "insulin-resistance" diabetes are frequently obese and require hypocaloric diets. Patients with beta cell failure require insulin therapy. Insulin therapy should always be integrated with the patient's meal and activity schedule; the primary dietary rule for the insulin-dependent diabetic is "follow a regular schedule for food intake." Youngsters with insulin-dependent diabetes must develop and mature normally. Diabetes is not caused by a high intake of "refined sugar;" in fact, high carbohydrate diets are beneficial to many diabetics. Saturated fats and cholesterol intake should be consumed in moderation. Uncontrolled diabetes is accompanied by elevated plasma cholesterol and triglyceride levels; insulin therapy is necessary to normalize these plasma lipids. Hypertriglyceridemia in the obese diabetic is best treated with hypocaloric diets that contain reduced quantities of carbohydrate. The "exchange" method is only one means of teaching patients about foods; other methods can be equally effective, provided the instruction is geared to the patient's intellectual level, is repeated frequently, and is evaluated. Physicians should seek the assistance of dietary counsellors when available.
REFERENCES 1. American Diabetes Association and American Dietetic Association: A Guide for Professionals: The Effective Application of "Exchange Lists for Meal Planning." 1977. 2. American Diabetes Association and American Dietetic Association: Exchange Lists for Meal Planning. 1976. 3. Bagdade, J. S., Bierman, E. L., and Porte, D., Jr.: Diabetic lipemia: A form of acquired fat-induced lipemia. New Eng. J. Med., 276:427-433, 1967. 4. Bennion, L. J., and Grundy, S. M.: Effects of diabetes mellitus on cholesterol metabolism in man. New Eng. J. Med., 296:1365-1371,1977. 5. Bierman, E. L., Albrink, M. J., Arky, R. A., et al.: Special report. Principles of nutrition and dietary recommendations for patients with diabetes mellitus. Diabetes, 20:633, 1971. 6. Bistrian, B. R., Blackburn, G. L., Flat!, J. P., et al.: Nitrogen metabolism and insulin requirements in obese diabetic adults on a protein-sparing modified fast. Diabetes, 25:494-504,1976.
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A. ARKY
7. Bruzell, J. D., Lerner, R. L., Hazzard, W. R., et al.: Improved glucose tolerance on high carbohydrate feeding in mild diabetes. New Eng. J. Med., 284:521-524, 1971. 8. Campbell, G. D.: Frequency of diabetes with special respect to diet in Diabetes. Proc. 7th Congress, International Diab. Fedn., Amsterdam Excerpta Medica. 9. Cleave, T. L.: On the causation of diabetes. In The Saccharine Disease. Bristol, John Wright and Sons Ltd, 1974. 10. Cohen, A. M., Bavly, S., and Poznanski, R.: Change of diet of Yemenite Jews in relation to diabetes and ischemic heart disease. Lancet, 1 :1399-1402, 1961. 11. Craig, 0.: Strictness, liberality and control. In Childhood Diabetes and Its Management. London, Butterworths, 1977. 12. Crapo, P. A., Reaven, G., and Olefsky, J.: Plasma glucose and insulin responses to orally administered simple and complex carbohydrates. Diabetes, 25:741-747,1976. 13. Cudworth, A. G., and Woodrow, J. D.: HL-A system and diabetes mellitus. Diabetes, 24:345-349, 1975. 14. Davidson, J. K: Controlling diabetes mellitus with diet therapy. Postgrad. Med., 59:114122, 1976. 15. Davidson, J. K: Plasma glucose lowering effect of caloric restriction in obesity-induced insulin treated diabetes mellitus. Diabetes, 26:355, 1977 (Suppl. 1, Abstract No. 12). 16. Frederickson, D. S.: Hyperlipoproteinemia with carbohydrate intolerance. In Fajans, S. S., and Sussman, K E., eds.: Diabetes Mellitus: Diagnosis and Treatment. New York., American Diabetes Association, Vol. In, 1971. 17. Ganda, O. P., and Soeldner, S. J.: Genetic, acquired and related factors in the etiology of diabetes mellitus. Arch. Intern. Med., 137:461-469, 1977. 18. Gottlieb, M. S., and Root, H. F.: Diabetes mellitus in twins. Diabetes, 17:693-704, 1968. 19. Harvald, B., and Hauge, M.: Hereditary factors elucidated by twin studies. Genetics and epidemiology of chronic diseases. U.S. Public Health Service Publication No. 1163, 1965. 20. Jenkins, D. J. A., Leeds, A. R., Gassull, M. A., et al.: Decrease in post-prandial insulin and glucose concentrations by guar and pectin. Ann. Intern. Med., 86:20-23, 1977. 21. Jenkins, D. J. A., Leeds, A. R., Wolever, T. M. S., et al.: Unabsorbable carbohydrate and diabetes. Decreased post-prandial hyperglycemia. Lancet, 2: 1 72-174, 1976. 22. Jenkins, D. J A., Wolever, T. M. S., Hockaday, T. D. R., et al.: Treatment of diabetes with guar gum. Lancet, 2:779-780,1977. 23. Kiehm, T. G., Anderson, J. W., and Ward, K: Beneficial effects of high carbohydrate, high fiber diet on hyperglycemic diabetic men. Amer. J. Clin. Nutr., 29:895-899,1976. 24. National Commission on Diabetes: Long-range plan to combat diabetes. Report to the Congress of the United States. December 10, 1975. Diabetes Forecast, 28 :6, 1975. 25. Olefsky, J., Reaven, G. M., and Farquhar, J W.: Effects of weight reduction on obesity. J. Clin. Invest., 53:64-76,1974. 26. Pyke, D. A.: General treatment of diabetes. Brit. Med. J., 3:268-270,1970. 27. Schernthaner, G., Mayr, W. R., Parker, M., et al.: HL-A8, W15, and T3 in juvenile onset diabetes mellitus. Horm. Metab. Res., 7:521-522, 1975. 28. Tattersall, R. B., and Pyke, D. A.: Diabetes in identical twins. Lancet, 2:1120-1125, 1972. 29. University Group Diabetes Program: A study of the effects of hypoglycemic agents on vascular complications in patients with adult-onset diabetes. Part 1 and Part 2. Diabetes, 19:747-830, 1971. 30. West, K M.: Diet therapy of diabetes: an analysis of failure. Ann. Intern. Med., 79:425-434, 1973. 31. West, K M., and Kalbfleisch, J. M.: Influence of nutritional factors on the prevalence of diabetes. Diabetes, 20:99-108, 1971. 32. Zifferblatt, S. M., and Wilbur, C. S.: Dietary counselling: some realistic expectations and guidelines. J. Am. Dietetic Assoc., 70:591-595, 1977. Mount Auburn Hospital Cambridge, Massachusetts 02138 end of article no. 13
Current Principles of Dietary Therapy of Diabetes Mellitus Ronald A. Arky, M.D. *
Two major reports concerned with diabetes mellitus published during the last several years emphasize the important role of diet in the management of this disorder. In 1971, the University Group Diabetes Program (UGDP) reported results of the first phase of a multicenter study, and concluded that "diet alone" may be more effective in prolonging the life of the diabetic than other therapeutic agents. 29 While controversy still stirs about this report, no one disputes the conclusions concerned with diet. In 1975, the National Commission on Diabetes recognized the marked increase in the prevalence of diabetes mellitus among Americans during the 8 year period 1965 through 1973. 24 In addition, the Commission noted that the chance for diabetes mellitus doubles for every 20 per cent of excessive weight. Hence, the strong implication that "diet" may play a role in the pathogenesis of diabetes. These documents, textbooks, and other instructional materials refer to "diet" as a therapeutic agent for the diabetic without elaborating specifics. The generic term "diet therapy" has multiple implications. For many, "diet therapy" is a concept based upon tradition and folklore since the quality and quantity of applicable investigative data are slim. This review examines current concepts of diet therapy and the principles on which these are based, and attempts to elaborate diet therapy in the context of the pathogenesis of the disease.
Diabetes Mellitus: Heterogeneity of the Syndrome Ideally, before therapy for a disorder is defined, some understanding of the pathogenesis of that disorder should be appreciated in order to determine the "site of action'" of the therapy. Diabetes mellitus is a heterogeneous syndrome with two basic etiologic lesions: one involves a disordered beta cell and is characterized by insulin deficiency; the other involves a resistance to the effectiveness of insulin on peripheral tissue as muscle, liver, and adipose tissue and is characterized by "Professor of Medicine, Harvard Medical School at the Mount Auburn Hospital; Chief of Medicine, Mount Auburn Hospital, Cambridge, Massachusetts
Medical Clinics of North America- Vol. 62, No. 4, July 1978
655
656
RONALD A. ARKY
normal or even elevated quantities of circulating insulin. Both major defects may be present in some diabetics. Patients with t~e first .lesion are "insulin-dependent" or "ketone-p~one". diab~tics. PatIent~, wIth the second or more common lesion are non-msuhn dependent and are frequently overweight. . Studies with monozygous twins confirm that from a genetIc standpoint there are also two types of ~iabetes.lH. 28 Interestingly en~ugh, ~he "insulin-dependent" variety of dIabetes appears to be a mamfestatIOn of both genetic and environmental factors. The non-insulin dependent form of diabetes on the other hand seems to be predominantly a genetic lesion for when it appears in one member of a pair of monozygic twins the other is always affected within a very short period of time.!7,!~ In addition to the twin studies, data concerned with the HLA system indicate that in insulin-dependent diabetics certain antigens in both the Band D locus are more prevalent and may serve as markers for potential diabetes.!3,27 Whether the presence of these HLA antigens predisposes individuals for specific infections remains speculative.
General Principles of Diet Therapy The primary objective in the dietary treatment of diabetes mellitus concerns the control of caloric intake! Youngsters with diabetes mellitus must receive sufficient numbers of calories to assure normal growth. Patients with the "non-insulin dependent" variety of diabetes tend to be overweight and frequently require hypocaloric diets. At initial contact, the physician must calculate the patient's ideal body weight. Table 1 gives a simplified system to approximate this value. Once the desired weight has been estimated, the caloric needs of the patient should be determined. This calculation depends upon the activity of the patient and whether or not weight loss or weight gain is deemed desirable. To determine an individual's basal caloric needs, multiply the "desired weight" by 10 (e.g., 120 x 10 = 1200 kilocalories). If the individual leads a sedentary life, add to this value the product of the desired body weight times 3; if the individual is moderately active add the desired body weight times 5; and if the individual pursues very strenuous activities, then add the desired body weight times 10. For overweight individuals, reducing the daily intake by 750 to 1000 kilocalories below the calculated requirements will induce a weight loss of 2 to 21f2 pounds per week. Pregnant or lactating women need 300 to 500 extra kilocalories per day to provide for normal fetal growth or milk production. Table L BUILD
Medium Frame Small Frame Large Frame
Estimating Desirable Body Weight! WOMEN
100 lb for first 5 ft of height, plus 5 lb for each additional inch Subtract 10 per cent Add 10 per cent
MEN
106 for the first 5 ft of height, plus 6 lb for each additional inch Subtract 10 per cent Add 10 per cent
DIETARY THERAPY
657
The second basic principle of dietary treatment is education. Most successful educational programs employ the team approach, where each member of the team (physician-dietitian-nurse) appreciates the importance of diet therapy and presents a unified approach. When the assistance of a dietary counsellor is unavailable, the physician must assume prime reponsibility and provide the diet prescription. Diet education is a constant process. Single encounters between the diet counsellor and the patient are useless. On each visit, the physician must emphasize the importance of caloric intake and evaluate the patient's compliance. Dietary instruction should never proceed unless the counsellor (physician-dietitian or nurse) assesses the patient's capability to comprehend the basic principles of diet management. In addition, the patient must acknowledge his/her responsibility for the success of this form of therapy. Some physicians advise setting up a "contract" before embarking upon an educational program. The third principle relates the integration of diet therapy with the other therapeutic modalities used by the diabetic. Activity and exercise are essential for all diabetics. Training facilitates the action of endogenous insulin. Insulin-dependent diabetics must coordinate their exercise activity and diet with the action of their medication. Such patien.ts require the intake of food at scheduled regular intervals and must have access to a readily available source of carbohydrate whenever participating in exercise.
SPECIFIC GUIDELINES FOR DIET THERAPY The Obese Diabetic Substantial data are available to demonstrate that weight loss in obese diabetics lowers the fasting blood sugar and improves glucose tolerance. Frequently, the loss of 7 to 10 Ib will be accompanied by marked improvement in fasting glucose levels. The precise method used to reduce weight seems irrelevant; apparently the absolute loss of weight accounts for the increase in the number of insulin receptors and the theoretical repair of intracellular metabolic effects that characterize the "insulin resistance" of obesity. Davidson has revised the teachings of Rollo and Naunyn and suggests "short term fasts" (one week) to initiate diet therapy in obese diabetics.14 Such an approach should be initiated only in patients who are: (1) under constant medical surveillance; (2) appreciate the severe complications that can result from starvation; and (3) have the ability to measure urine ketones and seek medical attention when symptomaticY Short term fasts must be followed by maintenance hypocaloric diets with the aim to achieve desired body weight. Bistrian and his colleagues advocated a protein-sparing modified fast for obese diabeticsY Such a diet, calculated to provide 1.2 or 1.4 gm of protein per kilogram of ideal body weight, is said to preserve lean body mass during weight loss. The protein-sparing modified fast not only improves diabetes but in some instances enables the patient to discon-
658
RONALD A. ARKY
tinue the use of exogenous insulin. These investigators suggest the use of a diet containing 1.3 gm of protein per kilogram of body weight daily as a maintenance measure to achieve body weight. Weight loss from whatever diet is ineffective unless the weight loss is maintained. Efforts to achieve desired body weight should be continuous and patients urged to lose 11/2 to 2 Ib per week. Unfortunately, there are no data to indicate that the improved glucose tolerance achieved by weight loss persists even if such weight loss is maintained, whether the improved glucose tolerance results in fewer anatomical complications of diabetes. Should carbohydrate be restricted in obese diabetics? Although· not universally accepted,2(; the American Diabetes Association in a policy statement maintains there is no need to restrict "disproportionately the intake of carbohydrate in the diet of most diabetic patients."5 Such a philosophy does not advocate unrestricted quantities of carbohydrate or encourage the use of "simple sugars;" however, it does recognize that diets with increased quantities of carbohydrate may result in improved glucose tolerance 7 and may not require increased quantities of insulin to control glucosuria. 2:l Total carbohydrate intake should represent 50 to 60 per cent of total energy consumption. Approximately 10 to 15 per cent of carbohydrate calories should be in the form of monosaccharides and disaccharides. Exceptions to this rule apply only to diabetics with hypertriglyceridemia that is aggravated by carbohydrate ingestion. In such individuals, carbohydrate calories should comprise 35 per cent of the total caloric input. The contention that carbohydrates, especially "refined sugars," are diabetogenic R-1O is challenged by the observation that the prevelance of diabetes in several populations around the world is "most impressive" and consistently associated with obesity and not with the intake of any specific foodstuff.:l ! Frequently, the introduction of large quantities of refined carbohydrate in a society reflects an improved economic standard in that society and is often accompanied by higher total caloric and fat intake, an increasingly sedentary pattern of life, and increased psychological stresses-all of which are diabetogenic. Several recent studies indicate that when diabetics consume meals that contain unabsorbable carbohydrates and guar gum and pectin, postprandial fluctuations in blood glucose as well as in the amount of glucosuria are reduced. 2(}-22 While further investigation is required to clarify the mechanism by which unabsorbable carbohydrates affect glucosuria and hyperglycemia, these preliminary observations indicate that high fiber diets may alleviate wide swings in blood glucose in the diabetic and reduce the need for hypoglycemic agents. Fats should comprise no more than 35 per cent of the total calories ingested by the obese diabetic. Debate continues about the preventive role of polyunsaturated fats in the pathogenesis of atherosclerosis. Prudent clinicians urge reduction in the consumption of animal fats with an eye toward weight reduction and maintaining normal plasma lipid levels. Protein calories should account for 10 to 15 per cent of the total energy intake of the adult.
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The Insulin-Dependent Diabetic Youngsters with diabetes must ingest an adequate number of calories to assure normal growth and maturation: formerly diabetic dwarfism was common among children placed on very restricted diets.l1 Diets that are nutritionally sound for non-diabetics are equally sound for diabetics. The sole limitation concerns "simple sugars" such as sucrose which may aggravate postprandial hyperglycemia. 12 While the symptoms of hyperglycemia and hypo glycemia are to be avoided, many insulin-dependent diabetics are refractory to both diet and insulin. The most important dietary concept that the insulin-requiring patient must accept pertains to the timing of meals. Dietary patterns must be tailored to fit the individual patient's activity and exercise schedule. While in the non-insulin dependent patient, food is usually divided into three meals per day, in the insulin-dependent individual, food is routinely divided into three meals and a bedtime snack and occasionally in youngsters into mid-afternoon or mid-morning snacks as well. For example, in the active youngster going to school, total calories may be divided such that 2/10's are given for breakfast, 2/10's at lunch, 1/10th as a mid-afternoon snack, 4/10's as the evening meal and the final 10th as a bedtime snack. Obviously, individualization must be the rule. Insulin-requiring patients must always have available a source of simple carbohydrate to counteract hypo glycemia. It is essential that these simple dietary concepts be presented to the insulin-requiring diabetic and his/her family immediately after the diagnosis is made. Young diabetics must appreciate the need for balanced meals eaten at regular intervals early in the course of their disease. Failure of the pediatrician or other physician to emphasize these basic principles at an early stage often results in individuals who are recalcitrant to a reasonable dietary approach and also to the general self-care measures that must be administered by the diabetic himself. Hyperlipoproteinemia in the Diabetic The relationship between diabetes and hyperlipoproteinemia has a palindromic quality: individuals with disordered lipid metabolisms have a high incidence of diabetes while, conversely, diabetics, especially those with persistent hyperglycemia, have a high incidence of hyperlipidemia.25 Often it is impossible to determine which of the two metabolic disorders has primacy. Three specific situations warrant discussion from the standpoint of dietary therapy: DECOMPENSATED DIABETES MELLITUS. This condition characterized by severe hyperglycemia and ketonemia is accompanied by elevated levels of triglycerides and cholesterol. Hypertriglyceridemia may represent an increase in both circulating chylomicrons and very low density lipoprotein (VLDL). Insulin therapy is not only necessary to stabilize carbohydrate metabolism in the uncontrolled state, but is also effective in lowering circulating triglycerides and cholesterol. Dietary therapy in the uncontrolled diabetic will be ineffective unless adequate insulin is administered. After the diabetes is stabilized, a low fat diet with less than 30 per cent of total calories as fat should be initiated.
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DIABETES, OBESITY AND HYPERTRIGLYCERIDEMIA (HYPER PRE-BETA LIPOPROTEINEMIA OR VLDL). This triad represents the most frequent clinical form of a lipid disorder observed in the diabetic population. Each component of the triad improves with weight 10ss.2.; Frequently, only a modest weight loss is required to effect significant reduction in triglyceride levels. Provided weight loss is maintained, the triglyceride levels will remain in the normal to high normal range. Some of these patients are "carbohydrate-sensitive" and in addition to a hypocaloric diet, the carbohydrate content of the diet should be reduced to 35 per cent or less of the total caloric intake. Patients with this triad should avoid alcohol. Occasionally, in spite of a hypocaloric diet, the diabetes progresses to an insulin-dependent type. In this situation, adequate insulin is required to prevent the overproduction of VLDL as well as to assure adequate amounts of tissue lipoprotein lipase and to assure adequate removal of chylomicrons. :1 DIABETES AND HYPERCHOLESTEROLEMIA (HYPER-BETA LIPOPROTEINEMIA OR HYPER-Low DENSITY LIPOPROTEINEMIA). In both the homozygous and heterozygous forms of hypercholesterolemia, diabetes may occur and usually is not severe. Such patients should receive diets that contain 300 mg or less of cholesterol per day and urged to strictly limit the ingestion of animal fats. Recently, Bennion and Grundy 4 demonstrated that in the uncontrolled diabetic, cholesterol balance and fasting plasma cholesterol are higher than when the patient's carbohydrate metabolism is stabilized with insulin. They concluded that insulin deficiency and hyperglycemia are accompanied by elevated levels of cholesterol that may play an important role in the pathogenesis of the macroangiopathy of diabetes.
Educational Issues The major issues concerning diet and diabetes are not difficult to define but are extremely difficult to relate to the practicing physician and patient. That efforts to convey the principles and ideas listed above have failed in the past is well documented.:JO Efforts to overcome the reluctance of physicians to accept principles such as hypocaloric diets and diets with higher carbohydrate content than formerly advocated may be beneficial comprise only one facet of the overall problem. More importantly, it is still uncertain how to assess patient comprehension, compliance, and continuance of dietary routine. Within the past two years, the American Diabetes Association and the American Dietetic Association have published a modification of the original Exchange List in an effort to update these lists and to provide a simplified basis for teaching patients the fundamentals about food and nutrition. 2 To aid the professional in the use of the Exchange Lists, these organizations have also developed a Professional Guide.! It is apparent that every diabetic requires instruction in dietary matters. However, a single session will not achieve the behavioral changes that are essential if results are to be expected from educational experiences. 32 Dietary counselling is an art and few physicians have the know-how or time to devote to this important therapeutic measure.
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Whenever possible, the physician should utilize the services of a diet counsellor and periodically refer the patient for follow-up teaching. Many dietitians have devised their own approach in teaching diabetics and several educators have suggested using instrumentation and audiovisual devices. Whatever the method used, some understanding of the patient's ability to comprehend and willingness to comply with instructions must be assessed. If there is one major gap in the educational processes used to teach the diabetic, the area of "diet instruction" must head the list.
SUMMARY Diabetes mellitus is a complex diathesis with two dominant pathogenic lesions: one, a failure of the islet's beta cells; the other, a resistance to the actions of insulin. Diet therapy for each patient should be designed within the framework of these pathogenic concepts. The most important objective of dietary treatment is control of total caloric intake to achieve desired body weight. Patients with "insulin-resistance" diabetes are frequently obese and require hypocaloric diets. Patients with beta cell failure require insulin therapy. Insulin therapy should always be integrated with the patient's meal and activity schedule; the primary dietary rule for the insulin-dependent diabetic is "follow a regular schedule for food intake." Youngsters with insulin-dependent diabetes must develop and mature normally. Diabetes is not caused by a high intake of "refined sugar;" in fact, high carbohydrate diets are beneficial to many diabetics. Saturated fats and cholesterol intake should be consumed in moderation. Uncontrolled diabetes is accompanied by elevated plasma cholesterol and triglyceride levels; insulin therapy is necessary to normalize these plasma lipids. Hypertriglyceridemia in the obese diabetic is best treated with hypocaloric diets that contain reduced quantities of carbohydrate. The "exchange" method is only one means of teaching patients about foods; other methods can be equally effective, provided the instruction is geared to the patient's intellectual level, is repeated frequently, and is evaluated. Physicians should seek the assistance of dietary counsellors when available.
REFERENCES 1. American Diabetes Association and American Dietetic Association: A Guide for Professionals: The Effective Application of "Exchange Lists for Meal Planning." 1977. 2. American Diabetes Association and American Dietetic Association: Exchange Lists for Meal Planning. 1976. 3. Bagdade, J. S., Bierman, E. L., and Porte, D., Jr.: Diabetic lipemia: A form of acquired fat-induced lipemia. New Eng. J. Med., 276:427-433, 1967. 4. Bennion, L. J., and Grundy, S. M.: Effects of diabetes mellitus on cholesterol metabolism in man. New Eng. J. Med., 296:1365-1371,1977. 5. Bierman, E. L., Albrink, M. J., Arky, R. A., et al.: Special report. Principles of nutrition and dietary recommendations for patients with diabetes mellitus. Diabetes, 20:633, 1971. 6. Bistrian, B. R., Blackburn, G. L., Flat!, J. P., et al.: Nitrogen metabolism and insulin requirements in obese diabetic adults on a protein-sparing modified fast. Diabetes, 25:494-504,1976.
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7. Bruzell, J. D., Lerner, R. L., Hazzard, W. R., et al.: Improved glucose tolerance on high carbohydrate feeding in mild diabetes. New Eng. J. Med., 284:521-524, 1971. 8. Campbell, G. D.: Frequency of diabetes with special respect to diet in Diabetes. Proc. 7th Congress, International Diab. Fedn., Amsterdam Excerpta Medica. 9. Cleave, T. L.: On the causation of diabetes. In The Saccharine Disease. Bristol, John Wright and Sons Ltd, 1974. 10. Cohen, A. M., Bavly, S., and Poznanski, R.: Change of diet of Yemenite Jews in relation to diabetes and ischemic heart disease. Lancet, 1 :1399-1402, 1961. 11. Craig, 0.: Strictness, liberality and control. In Childhood Diabetes and Its Management. London, Butterworths, 1977. 12. Crapo, P. A., Reaven, G., and Olefsky, J.: Plasma glucose and insulin responses to orally administered simple and complex carbohydrates. Diabetes, 25:741-747,1976. 13. Cudworth, A. G., and Woodrow, J. D.: HL-A system and diabetes mellitus. Diabetes, 24:345-349, 1975. 14. Davidson, J. K: Controlling diabetes mellitus with diet therapy. Postgrad. Med., 59:114122, 1976. 15. Davidson, J. K: Plasma glucose lowering effect of caloric restriction in obesity-induced insulin treated diabetes mellitus. Diabetes, 26:355, 1977 (Suppl. 1, Abstract No. 12). 16. Frederickson, D. S.: Hyperlipoproteinemia with carbohydrate intolerance. In Fajans, S. S., and Sussman, K E., eds.: Diabetes Mellitus: Diagnosis and Treatment. New York., American Diabetes Association, Vol. In, 1971. 17. Ganda, O. P., and Soeldner, S. J.: Genetic, acquired and related factors in the etiology of diabetes mellitus. Arch. Intern. Med., 137:461-469, 1977. 18. Gottlieb, M. S., and Root, H. F.: Diabetes mellitus in twins. Diabetes, 17:693-704, 1968. 19. Harvald, B., and Hauge, M.: Hereditary factors elucidated by twin studies. Genetics and epidemiology of chronic diseases. U.S. Public Health Service Publication No. 1163, 1965. 20. Jenkins, D. J. A., Leeds, A. R., Gassull, M. A., et al.: Decrease in post-prandial insulin and glucose concentrations by guar and pectin. Ann. Intern. Med., 86:20-23, 1977. 21. Jenkins, D. J. A., Leeds, A. R., Wolever, T. M. S., et al.: Unabsorbable carbohydrate and diabetes. Decreased post-prandial hyperglycemia. Lancet, 2: 1 72-174, 1976. 22. Jenkins, D. J A., Wolever, T. M. S., Hockaday, T. D. R., et al.: Treatment of diabetes with guar gum. Lancet, 2:779-780,1977. 23. Kiehm, T. G., Anderson, J. W., and Ward, K: Beneficial effects of high carbohydrate, high fiber diet on hyperglycemic diabetic men. Amer. J. Clin. Nutr., 29:895-899,1976. 24. National Commission on Diabetes: Long-range plan to combat diabetes. Report to the Congress of the United States. December 10, 1975. Diabetes Forecast, 28 :6, 1975. 25. Olefsky, J., Reaven, G. M., and Farquhar, J W.: Effects of weight reduction on obesity. J. Clin. Invest., 53:64-76,1974. 26. Pyke, D. A.: General treatment of diabetes. Brit. Med. J., 3:268-270,1970. 27. Schernthaner, G., Mayr, W. R., Parker, M., et al.: HL-A8, W15, and T3 in juvenile onset diabetes mellitus. Horm. Metab. Res., 7:521-522, 1975. 28. Tattersall, R. B., and Pyke, D. A.: Diabetes in identical twins. Lancet, 2:1120-1125, 1972. 29. University Group Diabetes Program: A study of the effects of hypoglycemic agents on vascular complications in patients with adult-onset diabetes. Part 1 and Part 2. Diabetes, 19:747-830, 1971. 30. West, K M.: Diet therapy of diabetes: an analysis of failure. Ann. Intern. Med., 79:425-434, 1973. 31. West, K M., and Kalbfleisch, J. M.: Influence of nutritional factors on the prevalence of diabetes. Diabetes, 20:99-108, 1971. 32. Zifferblatt, S. M., and Wilbur, C. S.: Dietary counselling: some realistic expectations and guidelines. J. Am. Dietetic Assoc., 70:591-595, 1977. Mount Auburn Hospital Cambridge, Massachusetts 02138 end of article no. 13
