Dipeptidyl peptidase-4 (DPP-4) inhibitors which increases GLP-1 and gastric inhibitory polypeptide (GIP) incretin hormone concentrations and GLP-1 receptor (GLP-1R) agonists are now widely used to treat type 2 diabetes and obesity [39,40,41]. The gene discussed is GLP1R; the disease is type 2 diabetes mellitus.