Pirogliride is the antidiabetic agent. It has been found to produce a hypoglycemic effect in nondiabetic rats, dogs, mice, and monkeys. To being three to four times more potent than tolbutamide, pirogliride also differs from the sulfonylureas in lowering blood glucose concentrations of streptozotocin-diabetic rats and db/db mice, and, moreover, oral administration to normal fasted dogs did not produce the characteristic rise in insulin concentrations observed with tolbutamide. Pirogliride potentiates glucose-induced insulin secretion from isolated islets. This effect is accompanied by a facilitated glucose metabolism. Pirogliride partially prevents the known inhibitory effects of mannoheptulose on glucose-induced secretion and utilization. Pirogliride was found to produce a concentration-dependent inhibition of gluconeogenesis in rat kidney cortex slices. hepatocytes and perfused liver. Pirogliride was metabolized in man to a small extent by oxidation of the 4-position of the phenyl ring.