Effects of hypocaloric diet and insulin therapy on metabolic control and mechanisms of hyperglycemia in obese non-insulin-dependent diabetic subjects.

We studied the effects of hypocaloric diet (500 kcal/d) and insulin therapy in 15 obese (body mass index greater than 30.0 kg/m2) non-insulin-dependent diabetic patients with secondary drug failure and poor metabolic control. The patients were randomly allocated either to hypocaloric diet (n = 8) or to insulin treatment (n = 7). After 2 weeks of treatment there was a significant improvement in the fasting blood glucose, in the mean diurnal glucose, in glucosuria, and in glucose response to a 75-g oral glucose load in both groups. No change in insulin secretion was seen in either group. Glucose disposal rates (GDR) improved significantly both in the diet-treated group (from 2.34 +/- 0.15 to 4.01 +/- 0.40 mg/kg/min, P less than .01) and in the insulin-treated group (from 2.46 +/- 0.33 to 2.77 +/- 0.29 mg/kg/min, P less than .01). The improvement was greater in the diet-treated group (71%) than in the insulin-treated group (13%, P less than .05). The increase of GDR in the diet-treated group was due to an increase of nonoxidative GDR (from 1.18 +/- 0.17 to 2.98 +/- 0.39 mg/kg/min, P less than .001) as assessed by indirect calorimetry. In the insulin-treated group there was a small increase both in oxidative and nonoxidative GDR, but the changes were not statistically significant. Hepatic glucose output (HGO) in a postabsorptive state decreased significantly both in the diet-treated group (from 2.49 +/- 0.15 to 2.04 +/- 0.10 mg/kg/min, P less than .01) and in the insulin-treated group (from 2.63 +/- 0.23 to 2.05 +/- 0.12 mg/kg/min, P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)