Effect of acute administration of metoclopramide on insulin secretion in man.

The effect of acute i.v. administration of 2.5 mg metoclopramide (MCP), an antidopaminergic agent with low serotoninergic activity, on blood insulin and glucose concentrations was studied in 9 healthy men. MCP was able to significantly decrease basal serum insulin levels (from 6.8 +/- 1.1 to 4.3 +/- 0.7 microU/ml in 120 min; p less than 0.025) with a parallel elevation in blood glucose (from 72.5 +/- 1.1 to 82.6 +/- 2.5 mg/dl in 120 min; p less than 0.01). These findings, which were not observed after placebo, and appeared not to be explained by the spontaneous occurrence of physiological oscillations of insulin and glucose plasma levels, are consistent with similar effects observed after administration of other antidopaminergic agents and with the stimulatory activity on insulin and glucagon release described during dopamine infusion in man.