[Effect of insulin on stimulated lipolysis in obesity with normal carbohydrate tolerance and unimpaired thyroid...

The effect of intravenous injection of 0.1 I.U./kg insulin on blood glucose response and on lipolysis, induced by intravenous infusion of 0.2 microgram/kg - min norepinephrine, were studied in 12 normal subjects and 17 obese patients with normal 50 g oral glucose tolerance test and normal thyroid function. In the obese group the insulin-induced hypoglycemia during norepinephrine-infusion was significantly less than in normal subjects. Moreover, the inhibition of norepinephrine-stimulated FFA and glycerol-release by insulin was significantly less in obesity as compared with the non-obese group. It is concluded that in obesity the action of insulin is decreased both in carbohydrate metabolism and in lipolysis. These results provide arguments for the role of an impaired antilipolytic insulin effect in the pathogenesis of hyperinsulinism in obesity.