Which oral hypoglycemic agent is most likely to cause hypoglycemia when used as monotherapy?

The correct answer is glipizide (Glucotrol) because it is a sulfonylurea, a class of oral hypoglycemic agents that stimulate insulin secretion from the pancreas. When used as monotherapy, glipizide can lead to hypoglycemia because it increases insulin levels regardless of blood glucose concentration. This mechanism can result in an excessive drop in blood sugar levels, especially in situations where food intake is reduced or physical activity is increased.

In contrast, metformin (Glucophage) primarily works by decreasing hepatic glucose production and improving insulin sensitivity, which does not typically cause hypoglycemia on its own. Pioglitazone (Actos) is a thiazolidinedione that also enhances insulin sensitivity but does not stimulate insulin secretion directly, making it much less likely to cause hypoglycemia as a standalone treatment. Acarbose (Precose) is an alpha-glucosidase inhibitor that slows carbohydrate absorption from the intestine, which can help control postprandial blood glucose levels but does not typically result in hypoglycemia when used alone.