Tolbutamide inhibits gastrin release in man.

Tolbutamide significantly decreased fasting plasma gastrin after 5 min of intravenous infusion in patients with atrophic gastritis, duodenal ulcer, or insulin-dependent diabetes mellitus (IDDM) as well as in healthy volunteers. Increased plasma insulin and decreased blood glucose were observed in patients with atrophic gastritis, duodenal ulcer and healthy volunteers, but not in patients with IDDM. Suppression of plasma gastrin in healthy volunteers was also observed following oral administration of tolbutamide. Despite the observed decrease in plasma gastrin, neither basal nor tetragastrin-stimulated acid output was changed for 30 min following tolbutamide infusion in healthy volunteers. Thus, our data suggest that tolbutamide inhibits gastrin release in man via mechanisms independent of changes in plasma insulin, blood glucose or acid secretion.