The current oral treatment options for T2DM are categorized into ten classes: 1) sulfonylureas, 2) meglitinides, 3) metformin (a biguanide), 4) thiazolidinediones (TZDs), 5) alpha-glucosidase inhibitors, 6) dipeptidyl peptidase IV (DPP-4) inhibitors, 7) bile acid sequestrants, 8) dopamine agonists, 9) sodium-glucose transport protein 2 (SGLT2) inhibitors, and 10) oral glucagon-like peptide 1 (GLP-1) receptor agonists. This evidence concerns the gene DPP4 and type 2 diabetes mellitus.