The treatment options for type 2 diabetes mellitus (T2DM) include various drug classes such as sulfonylureas (SUs), glinides (or meglitinides), biguanides, thiazolidinediones (also known as glitazones), α-glucosidase inhibitors, dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 (GLP-1) receptor agonists, and sodium-glucose linked transporter-2 (SGLT-2) inhibitors. This evidence concerns the gene GLP1R and type 2 diabetes mellitus.