GCG and type 2 diabetes mellitus: Besides, four classes of new agents are available on glycemic in T2DM, including the glucagon-like peptide-1 (GLP-1) analogue exenatide, dipeptidyl peptidase-4 (DPP-4) inhibitors sitagliptin and vildagliptin, and the long-acting insulin analogues, glargine and detemir [5].