DPP4 and type 2 diabetes mellitus: Sitagliptin is a selective dipeptidyl peptidase-4 inhibitor for the treatment of patients with type 2 diabetes and is sometimes used in combination with other classes of antidiabetic agents such as glinides (e.g., mitiglinide and repaglinide) and α-glycosidase inhibitors (e.g., miglitol).