Tolbutamide is an oral antihyperglycemic agent used for the treatment of non-insulin-dependent diabetes mellitus (NIDDM). It is structurally similar to acetohexamide, chlorpropamide and tolazamide and belongs to the sulfonylurea class of insulin secretagogues, which act by stimulating β cells of the pancreas to release insulin. Sulfonylureas lower blood glucose in patients with NIDDM by directly stimulating the acute release of insulin from functioning beta cells of pancreatic islet tissue by an unknown process that involves a sulfonylurea receptor (receptor 1) on the beta cell. Sulfonylureas inhibit the ATP-potassium channels on the beta cell membrane and potassium efflux, which results in depolarization and calcium influx, calcium-calmodulin binding, kinase activation, and release of insulin-containing granules by exocytosis, an effect similar to that of glucose.