Effect of low calorie diet and controlled fasting on insulin sensitivity and glucose metabolism in obese patients with type 1 diabetes mellitus.

Obesity in T1DM patients is associated with the components of metabolic syndrome. The influence of controlled fasting and low calorie diet (LCD) on insulin sensitivity and glucose metabolism was studied in 14 obese patients with type 1 diabetes mellitus (T1DM) (42.6+/-9.4 years, BMI 32.4+/-2.1 kg m(-2)). Insulin sensitivity in obese T1DM patients was measured using a hyperinsulinemic-euglycemic clamp before fasting, immediately after 7 days of fasting, and after 21 days of LCD. Glucose oxidation and non-oxidative glucose disposal were measured before and during the clamp by indirect calorimetry. In the control group of 13 of non-obese T1DM patients (36.9+/-13.9 years, BMI 22.6+/-2.1 kg m(-2)), only one hyperinsulinemic-euglycemic clamp was performed. Obese T1DM patients lost 6.1+/-1.1 kg after fasting and maintained reduction in body weight after 21 days of LCD. Fasting transiently reduced insulin-mediated glucose disposal in the clamp (from 9.69+/-1.48 to 6.78+/-1.21 mg min(-1) kg(-1), P<0.001). This was caused by reduced glucose oxidation after the fasting period (from 2.81+/-0.52 to 0.88+/-0.98 mg min(-1) kg(-1), P<0.001). We conclude that one week of fasting transiently decreased insulin-mediated glucose disposal in T1DM patients. This was caused by reduced glucose oxidation.