The effect of growth hormone on glucose metabolism and insulin secretion in man.

Pharmacological doses of GH are known to impair glucose tolerance. In the present study we have employed the euglycemic insulin and hyperglycemic clamp techniques to examine the effect of physiological elevations in plasma GH concentrations (27 ± 2 ng/ml) on the tissue responses to insulin and on glucose-stimulated insulin secretion. Three types of studies (low dose insulin clamp, high dose insulin clamp, and hyperglycemic clamp) were performed in young healthy volunteers before and after the infusion of GH (2 μg/kg-h) for 2 and 12 h. In the low dose insulin clamp studies, the plasma insulin concentration was acutely raised and was maintained at 59 ±4 μU/ml, while plasma glucose was maintained at basal levels. After 2 h of GH infusion, insulin-mediated glucose metabolism was slightly, although not significantly, decreased (4.48 ± 0.56 vs. 5.04 ± 0.39 mg/kg-min) in the control study. After 12 h of GH infusion, however, insulin-mediated glucose uptake decreased by 32 ± 9% (3.36 ± 0.40 mg/kg-min; P < 0.01). ...