Cetagliptin is an orally active inhibitor for dipeptidyl peptidase 4 ( DPP-4 ) and CYP2D6 ( IC 50 of 6 µM). Cetagliptin is a substrate for P-glycoprotein. Cetagliptin reduces the GLP-1 degradation, maintains the level of postprandial blood sugar, and can be used in type 2 diabetes mellitus research.