Among them, drugs used against type 2 diabetes mellitus, namely metformin, pioglitazone, sodium-glucose transporter-2 inhibitors (SGLT2i), glucagon-like peptide 1 receptor analogs (GLP-1 RAs), and dipeptyl-peptidase-4 inhibitors (DPP4i) have been used in both diabetic and non-diabetic individuals. This evidence concerns the gene GCG and type 2 diabetes mellitus.