Type 2 diabetes mellitus
Sitagliptin inhibits dipeptidyl peptidase-4 (DPP-4) enzyme resulting in prolonged active incretin levels. Incretin hormones (e.g., glucagon-like peptide-1 [GLP-1] and glucose-dependent insulinotropic polypeptide [GIP]) regulate glucose homeostasis by increasing insulin synthesis and release from pancreatic beta cells and decreasing glucagon secretion from pancreatic alpha cells.