Biochemical determination of training effects using insulin clamp technique.

Tissue sensitivity to insulin was evaluated in 6 trained athletes and 9 untrained controls using the euglycemic insulin clamp technique. The amount of glucose metabolism is a measure of overall tissue sensitivity to insulin. During insulin clamp study comparable plasma glucose (80-90 mg/dl) and insulin (90-100 microU/ml) were achieved in both groups. The glucose infusion rate in the athletes (10.70 +/- 0.32 mg/kg/min) was significantly higher than in the controls (7.37 +/- 0.23 mg/kg/min). During euglycemic hyperinsulinemia plasma FFA decreased by 80% while glycerol showed only a 20% reduction in both groups. Urinary catecholamine concentrations in the athletes were similar to those in the controls, and these levels did not change during the insulin clamp period. From these results, it might be concluded that tissue sensitivity to exogenous insulin is 45% higher in trained athletes and that physical exercise can reduce the insulin requirements in insulin-dependent diabetic patients in addition to being beneficial to noninsulin-dependent diabetics.