DPP4 and diabetes mellitus: 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