DPP4 and diabetic kidney disease: Recently, novel anti-diabetic agents, including incretin-related drugs, such as a dipeptidyl peptidase-4 (DPP-4) inhibitor, a glucagon-like peptide-1 (GLP-1) receptor agonist, and a sodium glucose cotransporter 2 (SGLT2) inhibitor, showed reno-protective effects against DKD [7,8,9,10,11].