Sulfonylurea: A class of oral hypoglycemic agents (pills and capsules taken to lower the level of blood glucose) by people with type 2 diabetes. The sulfonylureas increase the secretion of insulin by the pancreas.

There are two generations of sulfonylureas. The main difference between the first- and second-generation sulfonylureas is in the way they are eliminated from the body. As a consequence, second-generation sulfonylureas are usually taken less frequently each day than first-generation sulfonylureas and generally are preferred when there is poor function of the kidneys.

The first-generation sulfonylureas are acetohexamide (Dymelor), chlorpropamide (Diabinese), tolazamide (Tolinase), and tolbutamide (Orinase). The second-generation sulfonylureas include glipizide (Glucotrol and Glucotrol XL), glyburide (DiaBeta, Micronase, and Glynase PresTab) and glimepiride (Amaryl).