What is the mechanism of action for Dipeptidyl peptidase-4 inhibitors like sitagliptin and linagliptin?

Dipeptidyl peptidase-4 (DPP-4) inhibitors, such as sitagliptin and linagliptin, primarily work by inhibiting the enzyme DPP-4, which is responsible for the breakdown of incretin hormones like glucagon-like peptide-1 (GLP-1). By preventing this degradation, DPP-4 inhibitors increase the levels of active GLP-1 in the bloodstream.

GLP-1 plays a significant role in glucose metabolism; it enhances insulin secretion in a glucose-dependent manner, inhibits glucagon release, and promotes satiety. Therefore, the correct mechanism involved here is the inhibition of the breakdown of incretin GLP-1, leading to an increased physiological effect of this hormone, which helps control blood sugar levels in individuals with type 2 diabetes.

Other options, while related to functions of diabetes medications, do not accurately describe the specific action of DPP-4 inhibitors. For example, stimulating insulin release or binding to GLP-1 receptors could involve different classes of medications or mechanisms. DPP-4 inhibitors do not directly delay carbohydrate absorption; that action is more associated with other types of medications. Thus, the key points lie in the unique role D