Which drug is an anti-diabetic agent?

• A. Gliclazide
• B. Acarbose
• C. Pioglitazone
• D. Metformin

Answer: (D)

Metformin is an oral anti-diabetic agent that works mainly by reducing hepatic glucose production and improving insulin sensitivity in muscle and fat, with a modest decrease in intestinal glucose absorption. It does not stimulate insulin release, so it has a relatively low risk of causing hypoglycemia when used alone, and it tends to be weight-neutral or even modestly weight-reducing. These features, along with strong evidence from trials and its status as a first-line therapy for type 2 diabetes, make it the best answer.

The other drugs here belong to different antidiabetic classes with distinct profiles: a sulfonylurea increases insulin secretion from the pancreas (higher hypoglycemia risk and potential weight gain); an alpha-glucosidase inhibitor slows carbohydrate digestion to blunt postprandial glucose spikes; a thiazolidinedione improves insulin sensitivity but can cause edema and weight gain. While all are antidiabetic, metformin’s combination of mechanism, safety, and guideline position explains why it’s the selected option.