Insulin sensitivity during very-low-calorie diets assessed by minimal modeling

The time course of plasma glucose, insulin, and C-peptide after intravenous glucose (300 mg/kg body wt) injection was analyzed with minimal model approach in nine normal females and seven obese females. Glucose tolerance, estimated by glucose assimilation coefficient ([K.sub.G]), was positively correlated with glucose effectiveness ([S.sub.G]), but not correlated with peripheral insulin sensitivity ([S.sub.I]) in obese females as well as normal females. These factors were estimated before and after weight loss with 1.8-MJ (420-kcal) very-low-calorie diets (VLCDs) or with 2.5-3.3-MJ (600-800-kcal) low-calorie diets in two obese subjects. [K.sub.G], and glucose effectiveness decreased after acute weight loss with VLCD, although insulin sensitivity increased. Weight loss with low calorie diets resulted in improvement of [K.sub.G], and glucose effectiveness. These results suggest that a significant amount of glucose is taken up through insulin-independent mechanisms during the intravenous glucose tolerance test (ivGTT) in these subjects. This insulin-independent glucose uptake may be an important determinant of the fate of glucose in obese females as well as normal females. Am J Clin Nutr 1992;56:179S-81S.