GCG and diabetes mellitus: Major classes of drugs used in the treatment of DM are insulins, sulfonylureas (SUs), thiazolidinediones (TZDs), biguanides, meglitinides, α-glucosidase inhibitors (AGIs), dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 (GLP-1) agonists, sodium-glucose cotransporter 2 (SGLT2) inhibitors, and dopamine agonists [3].