DPP-4 inhibitor, a serine protease inhibitor on the cell surface, has the effect of inhibiting inactivation of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulin secreting polypeptide (GIP), thereby increasing the level of endogenous GLP-1 and GIP, promoting insulin release, and inhibiting glucagon secretion, which increase level of insulin and play an important role in the treatment of hyperglycemia. The gene discussed is GCG; the disease is Hyperglycemia.