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Diabetes - Prevention Objective: To examine prospectively the relationship between glycemic diets, low fiber intake, and risk of non-insulin dependent diabetes mellitus.
Design: Cohort study Setting: In 1986, a total of 65,173 US women 40 to 65 years of age and free from diagnosed cardiovascular disease, cancer, and diabetes completed a detailed dietary questionnaire from which we calculated usual intake of total and specific sources of dietary fiber, dietary glycemic index, and glycemic load.
Main Outcome Measure: Non-insulin dependent diabetes mellitus.
Results: During 6 years of follow-up, 915 incident cases of diabetes were documented. The dietary glycemic index was positively associated with risk of diabetes after adjustment for age, body mass index, smoking, physical activity, family history of diabetes, alcohol and cereal fiber intake, and total energy intake. Comparing the highest with the lowest quintile, the relative risk (RR) of diabetes was 1.37 (95% confidence interval[CI],1.09 - 1.71, P trend=.005). The glycemic load ( an indicator of a global dietary insulin demand) was also positively associated with diabetes (RR=1.47; 95% CI, 1.16-1.86, P trend=.003). Cereal fiber intake was inversely associated with risk of diabetes when comparing the extreme quintiles (RR=0.72, 95% CI, 0.58 - 0.90, P trend=.001). The combination of a high glycemic load and a low cereal fiber intake further increased the risk of diabetes (RR=2.50, 95% CI, 1.14 - 5.51) when compared with a low glycemic load and high cereal fiber intake.
Conclusions: Our results support the hypothesis that diets with a high glycemic load and a low cereal fiber content increase risk of diabetes in women. Further, they suggest that grains would be consumed in a minimally refined form to reduce the incidence of diabetes.Reference: JAMA 1997; 227: 472-477 The enormous morbidity and mortality associated with type II diabetes imposes a heavy burden on society - in terms of both human suffering and economic resources. With the incidence increasing to epidemic proportions among some segments of the population, identifying ways to prevent the disease has become a major public health concern. Drs Mudaliar and Henry discuss the rationale for early identification of at-risk patients, along with nonpharmacologic and pharmacologic approaches to primary prevention. Non-insulin dependent (type II) diabetes mellitus is a common, chronic disease affecting between 12 and 15 million Americans - about 7% of the adult population. The incidence has been steadily growing and is rapidly approaching epidemic proportions in the elderly and certain minority populations, including African Americans, Hispanic Americans, Asian and Pacific Island Americans, and Native Americans. Diabetes is the leading cause of adult blindness, end-stage kidney failure, and nontraumatic amputations in the United States. In addition, type II patients have a twofold to fourfold increase in risk for cardiovascular disease and stroke. Important factors associated with an increased risk for the disorder include obesity, advanced age, family history of diabetes, minority race, gestational diabetes, sedentary lifestyle, and impaired glucose tolerance (IGT). It is known that the prediabetic state may be present for many years before the disease actually develops. Ref: Diabetes Prevention, Vol 101, No 1, January 1997, Postgraduate Medicine
Approaches to Prevention A number of options are available for attempting to avert onset of type II diabetes.
Weight reduction Obesity is often associated with hyperinsulinemia and contributes to insulin resistance. On the other hand, weight loss has repeatedly been shown to reduce - and even correct - insulin resistance. Therefore, aggressive efforts to manage weight present an attractive intervention option for high-risk individuals.Unfortunately, for most people, the likelihood of losing significant weight is limited, and the likelihood of regaining weight is high. In one study, only one third of subjects were able to sustain weight loss of more than 10% of their initial body weight for up to 12 months - despite caloric restrictions and use of appetite suppressants. Nonetheless, efforts at weight management may be beneficial for some patients, particularly if incorporated in an overall program including behavior modification and exercise.
Diet The use of a diet low in calories and in saturated fat (<10% of total calories) is an ideal strategy for preventing type II diabetes. Saturated fats have been implicated in the development of insulin resistance and may speed up development of diabetes.Short-term studies have shown a small but consistently positive relationship between increased use of monounsaturated fat in the diet and improved insulin action. Along with reducing saturated fat, increases in high-fiber, complex-carbohydrate foods and use of monunsaturated and polyunsaturated fats have been advocated. These dietary modifications are also recommended for preventing cardiovascular disease. Since type II patients are also at increased risk for cardiovascular disease, they may derive significant benefits from changing their diets.
Exercise A sedentary lifestyle is another important risk factor for type II diabetes. In fact, some retrospective studies have shown a dose-insulin action through extrapancreatic mechanisms. Although investigators have studied the role of sulfonylure as in preventing transition of IGT to diabetes, no consistent benefit has been demonstrated. It is possible that these drugs reverse the secondary, hyperglycemia-induced, component of insulin resistance only in overtly diabetic patients. A concern with use of these agents is the risk of hypoglycemia.Among the Biguanides, metforminhydrochloride (Glucophage) is the form currently available for clinical use. Its efficacy in reducing glycemia in type II diabetes without weight gain or significant hypoglycemia is well established. Metformin is reported to lower basal hepatic glucose production in diabetes, but evidence supporting an effect on insulin sensitivity has been conflicting. In some studies, use of metformin has been associated with significant weight loss, which may affect insulin action. Of the antidiabetic drugs currently available and in common clinical use, metformin appears to have the greatest potential for preventing development of type II diabetes. Other pharmacologic agents that improve glucose tolerance include insulin and alpha-glucosidase inhibitors such as acarbose (Precose), which is a competitive inhibitor of alpha glucosidase (an intestinal brush-border enzyme). By delaying the hydrolysis of ingested complex carbohydrates, acarbose causes a dose-dependent reduction in postprandial glucose and insulin levels. However, the efficacy of alpha-glucosidase inhibitors in diabetic prevention has not been demonstrated in large clinical trials. The same is true of insulin. Moreover, the risk of hypoglycemia with insulin and increased flatulence with acarbose limit the long-term usefulness of these agents. An exciting development is the recent introduction of a new class of oral antidiabetic drugs called thiazolidinediones. These appear to work principally by improving insulin resistance. The most extensively studied compound of this class, which is currently undergoing phase III trials in humans, is troglitazone. Although the exact mechanism of action is still unknown, troglitazone appears to directly affect insulin action in liver, skeletal muscle, and adipose tissue. Preliminary results in patients with both diabetes and IGT demonstrate substantial lowering of glucose levels associated with reduced circulating insulin resistance. Since insulin resistance is probably a precursor of type II diabetes, these compounds may have significant potential for preventing type II diabetes.
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