The changes were associated with increased resistance in the renal cortical artery and decreased renal cortical blood flow. Nimbidiol treatment decreased elevated M1 macrophage, pro-inflammatory cytokine and ECM accumulation to ameliorate renal fibrosis and improve arterial resistance and blood flow of the renal cortex and renal function via downregulation of TGF-β1, p-Smad2/3, p-P38, p-ERK1/2 and p-JNK in type-1 diabetic kidney. This evidence concerns the gene SMAD2 and renal fibrosis.