The number of patients with type 2 diabetes mellitus (T2DM) is increasing, and there will be 380 million people with T2DM by 2025.4, 5 In order to treat T2DM, the use of oral hypoglycemic agents (OHAs), including metformin, α‐glucosidase inhibitors, sulfonylureas, thiazolidinediones, dipeptidyl peptidase‐4 (DPP‐4) inhibitors, and sodium glucose cotransporter‐2 (SGLT‐2) inhibitors, is recommended.6, 7 In particular, metformin (the first choice in T2DM) and incretin‐related drugs such as DPP‐4 inhibitors and glucagon‐like peptide‐1 (GLP‐1) analogs have good glycemic control.8, 9, 10, 11. This evidence concerns the gene GCG and type 2 diabetes mellitus.