Effect of impaired glucose tolerance and type II diabetes on resting metabolic rate and thermic response to a glucose meal in obese women

We examined the hypothesis that patients with impaired glucose tolerance or type II diabetes mellitus have reduced glucose-induced thermogenesis and that this perpetuates obesity in them by reducing energy expenditure. The thermic response after a 75-g glucose meal for 150 minutes was significantly lower in five obese women with diabetes (7.18 ± 1.8 kcal) and five other obese women with impaired glucose tolerance (6.4 ± 0.8 kcal) than in five obese women with normal glucose tolerance (16.7 ± 2.4 kcal) and five lean healthy control subjects (14.0 ± 2.2 kcal, P < 0.05). However, obese women with diabetes or impaired glucose tolerance had a significantly higher resting metabolic rate (RMR) (307.0 ± 9.7 mL O₂/min) than predicted for them on the basis of their age, body weight, and total body potassium (274.8 ± 8.0 mL O₂/min, p < 0.01). The predicted RMR in obese women with normal glucose tolerance test (GTT) (286.0 ± 5.0 mL O₂/min) was not different from their observed RMR (272.0 ± 6.0). Thus the total energy expenditure during the meal of obese women with diabetes ( 254 ± 32 kcal 150 min) and obese women with impaired glucose tolerance ( 221 ± 5 kcal 150 min) was higher than that of obese women with normal glucose tolerance ( 201 ± 9 kcal 150 min). All three obese groups had a higher total energy expenditure than the lean group ( 158 ± 4 kcal 150 min, P < 0.001). It is concluded that even though in patients with type II diabetes or impaired glucose tolerance there is a reduction in the increment in metabolic rate after a glucose meal, they also have elevated RMR and total energy expenditure. Obese patients with diabetes and impaired glucose tolerance require more kcal/LBM (lean body mass) to maintain their body weight than the control subjects.