Which of the following are sulfonylureas?

• A. Metformin
• B. Glipizide, glyburide, chlorpropamide
• C. Insulin
• D. Acarbose

Answer: (B)

Sulfonylureas work by stimulating the pancreas to release more insulin. They do this by binding to a receptor on the beta-cell potassium channel (the SUR1-associated KATP channel), which closes the channel. The cell then depolarizes, calcium channels open, and stored insulin is released, helping to lower blood glucose in type 2 diabetes.

The sulfonylureas in the list are glipizide, glyburide, and chlorpropamide. Metformin acts mainly by reducing hepatic glucose production and improving insulin sensitivity, not by increasing insulin release. Insulin is the hormone itself, not a sulfonylurea. Acarbose delays carbohydrate absorption in the gut by inhibiting intestinal enzymes, rather than stimulating insulin secretion.