Alpha cell function in health and disease: influence of glucagon-like peptide-1
The inhibitory effect of somatostatin on insulin, glucagon and growth hormone secretion was studied in 5 patients with diabetes mellitus. In three maturity onset diabetics, somatostatin infusion abolished the insulin rise induced by breakfast and oral glucose, and in 2 of them, inhibited the basal insulin secretion by 50% seen during control studies. Concomitantly, there was a marked and prompt reduction of glucagon levels (50%) with a sustained effect. The plasma glucose levels were either unchanged or slightly increased. Following the somatostatin infusion, there was a prompt rebound increase in both insulin and glucagon levels with a relatively stable plasma glucose concentration. In contrast, a drastic reduction of plasma glucose in face of a relatively small fall in plasma glucagon in response to somatostatin infusion was observed in 2 insulin-dependent diabetics. In all patients, the episodic release of growth hormone seen during the control day was abolished during somatostatin infusion.