Exercise and energy/substrate use in blacks with NIDDM

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DESCRIPTION (adapted from the application) African Americans (AA) have a 2-3 fold higher prevalence of type 2 diabetes mellitus (DM), greater disease-associated morbidity and mortality and earlier age of onset than Caucasian Americans (CA). The etiology for these differences is unclear but has been related to insulin resistance and an increased prevalence of obesity. Thus, investigations into racial differences in metabolic and energy aspects of type 2 DM in AA will provide important data on the increased prevalence of both obesity and type 2 DM in the AA population when compared to CA. The aims of the study include: 1) To examine racial differences in substrate utilization, energy expenditure, insulin sensitivity, glucose effectiveness and beta cell function before and after chronic exercise in AA and CA subjects with type 2 DM, 2) To determine the effects of chronic exercise on the resting metabolic rate (RMR), postprandial thermogenesis and substrate oxidation in CA and AA subjects with type 2 DM, 3) To compare the effects of resistance vs. aerobic training on substrate oxidation and energy expenditure and 4) to determine whether the sequential pattern of exercise is associated with different metabolic and energy consequences in CA and AA subjects with type 2 DM. The proposed Study is a prospective exercise intervention program in AA and CA subjects with type 2 DM. The study population will consist of 75 AA and 75 CA subjects with type 2 DM. The time frame for study participation will be 26 weeks. On study day 1, each subject will undergo screening laboratory data, assessment of glucose turnover rates with D-3 3H glucose infusion and concomitant OGTT and indirect calorimetry. On study day 2, each subject will have a dual energy x-ray absorptiometry (DEXA) scan and a magnetic resonance imaging (MRI) scan for assessment of body composition and body fat distribution. On study day 3, insulin sensitivity, glucose effectiveness and beta-cell function will be assessed using the Bergman Minimal Model Methodology. The subjects will then be randomly allocated to begin either 8 weeks of aerobic or resistance training with a crossover to the other exercise training program for an additional 8 weeks. Each metabolic and anthropometric study will be performed four times; upon entry to the study, after completion of each of the exercise programs, and 8 weeks after the exercise intervention. This study will provide insights into metabolic abnormalities associated with type 2 DM in AA and the importance of exercise intervention in AA and CA. We believe the findings of tile present Study could be the basis of prescribing an effective exercise modality in AA with type 2 diabetes mellitus.