It has been well established that inhibition of dipeptidyl peptidase-4 (DPP-4) reduces blood glucose levels in both fasting and postprandial states, and preserves pancreatic β-cell function in patients with type 2 diabetes. The mechanism of action of DPP-4 inhibitors is to increase levels of active incretin, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), which stimulate insulin secretion as well as insulin biosynthesis while inhibiting glucagon release from pancreatic islets.