Gliptins constitute a class of drugs increasingly used for the treatment of type 2 diabetes mellitus, inhibiting dipeptidyl peptidase 4 (DPP4), the enzyme that inactivates the incretin hormones such as glucagon-like peptide 1 (GLP1) and glucose dependent insulinotropic polypeptide (GIP). This evidence concerns the gene GCG and type 2 diabetes mellitus.