What is the mechanism of action of DPP-4 inhibitors in glucose regulation?

• A. They stimulate insulin release directly from pancreatic beta cells independent of incretins.
• B. They block glucose absorption from the gut.
• C. They inhibit degradation of incretins by DPP-4, prolonging their action, increasing insulin secretion and suppressing glucagon.
• D. They increase hepatic glucose production.

Answer: (C)

DPP-4 inhibitors work by preventing the breakdown of incretin hormones (like GLP-1 and GIP) so their action lasts longer after meals. With more active incretins, the pancreas releases more insulin in response to rising blood glucose and suppresses glucagon release, which together lower postprandial glucose. This effect is glucose-dependent, reducing the risk of hypoglycemia. They do not directly stimulate insulin release without incretins, do not block gut glucose absorption, and do not increase hepatic glucose production.