Oral antihyperglycemic agents (AHAs), including biguanides, thiazolidinediones (TZDs), alpha-glucosidase inhibitors, meglitinides, dipeptidyl peptidase 4 (DPP-4) inhibitors, and sulfonylureas (SUs), can be used either individually or in combination to treat diabetes. This evidence concerns the gene DPP4 and diabetes mellitus.