Dipeptidyl peptidase 4 (DPP4) is involved in the regulation of incretins GLP-1 and GIP that control blood sugar, and DPP4 inhibitors Sitagliptin, Vildagliptin and Saxagliptin are approved as drugs to treat type 2 diabetes [26]–[28]. Here, DPP4 is linked to type 2 diabetes mellitus.