Twenty-four-hour energy expenditure in Pima Indians with type 2 (non-insulin-dependent) diabetes mellitus.

To assess the impact of Type 2 (non-insulin-dependent) diabetes mellitus on energy metabolism, 24-h energy expenditure, basal metabolic rate and sleeping metabolic rate were measured in a respiratory chamber in 151 Pima Indians, 102 with normal glucose tolerance (67 male/35 female, (mean +/- SD) 28 +/- 7 years, 99 +/- 24 kg, 32 +/- 9% body fat) and in 49 with Type 2 diabetes (22 male/27 female, 35 +/- 11 years, 107 +/- 33 kg, 39 +/- 7% body fat), after at least 3 days on a weight maintaining diet. After adjustment for differences in fat-free mass, fat mass, age and sex, 24-h energy expenditure, basal metabolic rate and sleeping metabolic rate were significantly higher in diabetic patients than in control subjects (72 kcal/day, p less than 0.05; 99 kcal/day, p less than 0.005; 99 kcal/day, p less than 0.001 respectively). Spontaneous physical activity was similar in both groups whereas the thermic effect of food, calculated as the mean energy expenditure corrected for activity throughout the day above sleeping metabolic rate and expressed as a percentage of energy intake, was significantly lower in Type 2 diabetic patients (17.1 +/- 7.1 vs 19.8 +/- 5.6%, p less than 0.05). Adjusted values of 24-h energy expenditure, basal metabolic rate and sleeping metabolic rate were correlated with hepatic endogenous glucose production (r = 0.22, p less than 0.05; r = 0.22, p less than 0.05; r = 0.31, p less than 0.01 respectively). Therefore, increased basal and sleeping metabolic rates, resulting in increased 24-h sedentary energy expenditure may play a role in the weight loss so often observed in Type 2 diabetic subjects in addition to the energy loss from glycosuria.