Which diabetic medication would you least associate with an adverse effect of hypoglycemia?

• A. Glipizide
• B. Glyburide
• C. Metformin
• D. Chlorpropamide

Answer: (C)

The key idea is how these drugs affect glucose levels. Metformin lowers blood sugar mainly by reducing hepatic glucose production and improving how the body uses insulin, but it does not stimulate the pancreas to release more insulin. That’s why it has a very low risk of causing hypoglycemia when used alone. In contrast, the sulfonylureas—glipizide, glyburide, and chlorpropamide—work by forcing the pancreas to secrete more insulin, which can lead to low blood sugar, especially if meals are skipped or if kidney or liver function is impaired. So metformin is the medication least associated with hypoglycemia. (Note: the hypoglycemia risk rises if metformin is combined with other insulin secretagogues or insulin.)