On the diabetogenic effect of growth hormone in man: effects of growth hormone on glucagon and insulin secretion

The effects of human growth hormone (GH) on glucose homeostasis and the secretion of insulin and glucagon was investigated in eighteen healthy subjects. GH (40 microgram/kg) was given as a 30 min i.v. infusion and was followed immediately, or after 60 min, by either a glucose infusion, or an i.v. L-arginine infusion or i.v. insulin (0.05 IU/kg). An insulin-like effect of GH was seen about 15 min after the start of the GH infusion, and became a diabetogenic action 90 min later. Basal and glucose stimulated insulin secretion were suppressed 60 min after the start of the GH infusion, while insulin response to i.v. L-arginine, on the whole, was uninfluenced. Basal glucagon as well as glucagon response to arginine or hypoglycaemia were uninfluenced by GH. GH did not alter the degree of hypoglycaemia reached after i.v. insulin, whereas the rapidity of blood glucose fall was significantly decreased. The restitution of blood glucose after its nadir was not modified by the hormone. These results demonstrate that the diabetogenic action of GH is not mediated by GH effects on glucagon secretion, and that GH is of little importance in the acute counter-regulation of insulin-induced hypoglycaemia.