DPP4 and diabetes mellitus: In the clinic, glucose-lowering agents such as biguanide, sodium-glucose transporter 2 (SGLT2) inhibitor, dipeptidyl peptidase 4 (DPP-4) inhibitors, glucagon-like peptide 1 (GLP-1) and Thiazolidinediones can not only control blood glucose but also improve endothelial function by targeted regulation of oxidative stress, thus preventing/improving vascular complications of diabetes [108] (Table 1).