Dipeptidyl peptidase 4 (DPP4, EC 3.4.14.5), also known as CD26, is a type II transmambrane serine protease widely distributed on the surface of human cells, which can decompose the peptide bonds of proline or alanine residues at the second position of the N-terminus of the peptide chain. DPP4 can rapidly decompose incretin that promotes the reduction of blood glucose levels in organisms, and DPP4 inhibitors, as a new hypoglycemic drug, achieve the purpose of regulating blood sugar by inhibiting DPP4 activity.