What is the mechanism of action of DPP-4 inhibitors?

• A. Prolonged incretin activity by inhibiting dipeptidyl peptidase-4, increasing endogenous GLP-1 and GIP levels
• B. Inhibit renal glucose reabsorption
• C. Stimulate insulin secretion directly
• D. Delay carbohydrate absorption in the intestine

Answer: (A)

DPP-4 inhibitors work by blocking the enzyme that quickly breaks down incretin hormones after a meal. By inhibiting DPP-4, they raise levels of the gut hormones GLP-1 and GIP. These incretins amplify insulin release from the pancreatic beta cells in a glucose-dependent way and also help restrain glucagon secretion when blood glucose is high. The result is better control of postprandial glucose with a lower risk of hypoglycemia, since the effect kicks in mainly when glucose rises. This action is distinct from drugs that stop renal glucose reabsorption or that delay carbohydrate absorption, which explains why those mechanisms aren’t correct here.