The effect of fasting and vitamin E on insulin action in obese type 2 diabetes mellitus.

The influence of either short-term fasting or vitamin E administration on insulin action was studied in two groups of obese Type 2 diabetic patients. Twelve patients underwent 7 days of fasting (group A), whereas 600 mg of vitamin E was administered daily during 3 months in 9 diabetic patients (group B). Insulin action was examined by using hyperinsulinemic isoglycemic clamps (insulin infusion rate, 1.0 mU/kg/min) and insulin receptors on erythrocytes before and after respective regimens. An increase of glucose disposal rate (29.5 +/- 8.9 vs. 24.0 +/- 7.5 mumol/kg/min, p < 0.01) and an increase of metabolic clearance rate of glucose (4.0 +/- 2.5 vs. 2.3 +/- 0.9 mL/kg/min, p < 0.01) were observed in group A after fasting. On the contrary, decreases of glucose disposal rate (21.3 +/- 8.5 vs. 26.6 +/- 9.8 mumol/kg/min, p < 0.02), metabolic clearance rate of glucose (2.9 +/- 0.8 vs. 3.7 +/- 1.7 mL/kg/min, p < 0.05), and insulin receptor number (p < 0.01) were found after vitamin E administration as compared with pretreated values. A worsening of diabetes control as observed by an increase of HbA1C (p < 0.01) was present in the latter group. In summary, we found an improvement of insulin action after short-term fasting in contrast with the worsening of metabolic parameters after vitamin E administration in obese Type 2 diabetic patients.