What is the mechanism of action of metformin in type 2 diabetes?

• A. Increases pancreatic insulin secretion.
• B. Inhibits glucose absorption in the intestine.
• C. Decreases hepatic glucose production and increases peripheral insulin sensitivity; does not cause hypoglycemia when used alone.
• D. Directly stimulates glycolysis in muscle.

Answer: (C)

The mechanism being tested is how metformin lowers blood sugar without causing hypoglycemia, focusing on the liver and peripheral tissues. Metformin primarily reduces hepatic glucose production by inhibiting gluconeogenesis, which lowers the amount of glucose released into the bloodstream. It also improves insulin sensitivity in peripheral tissues, especially skeletal muscle, helping glucose to be taken up and utilized more effectively.

Because metformin does not stimulate pancreatic insulin secretion, it does not by itself provoke hypoglycemia when used alone. There is a minor effect on intestinal glucose absorption, but this is not its main action.

So, the best statement describes metformin as decreasing hepatic glucose production and increasing peripheral insulin sensitivity, with a low risk of hypoglycemia when used alone.