GCG and renal fibrosis: Hence, the present experiment was performed to explore whether the DPP-4 inhibitor sitagliptin (SG) and GLP-1R agonist liraglutide (Li) have a protective effect against renal fibrosis caused by monocrotaline- (MCT-) induced renal microcirculation lesions [24] and whether the protective effect of DPP-4 inhibition on renal fibrosis is mediated by GLP-1.