Sitagliptin, a dipeptidyl peptidase‐4 (DPP‐4) inhibitor, inhibits the metabolism and inactivation of the incretin hormones glucagon‐like peptide‐1 (GLP‐1) and glucose‐dependent insulinotropic polypeptide (GIP), and is approved as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. This evidence concerns the gene GIP and diabetes mellitus.