Effect of metergoline, a powerful and long-acting antiserotoninergic agent, on insulin secretion in normal subjects and in patients with chemical diabetes.

The effect of metergoline on insulin secretion has been evaluated in normal subjects and in patients with chemical diabetes. The repeated administration of metergoline, 2 mg at four-hour intervals to give a total of 24 mg, has enhanced insulin secretion in response to i.v. glucose in normal subjects but not in chemical diabetics. No changes in blood glucose pattern were observed. Under similar conditions, metergoline administration caused a slight but significant decrease in arginine-induced insulin release, both in normal subjects and in chemical diabetics. These results support the concept of a serotoninergic control of insulin secretion and suggest that serotonin exerts different effects on insulin release according to the different stimuli.