In our study, we also found that DMP-1 had protective effects on DKD in rats induced by STZ-injection, which was demonstrated as following criteria: 1) a significant reduction in levels of urea (p < 0.05), BUN (p < 0.05), UCr (p < 0.05), β2-MG (p < 0.05) and mALB (p < 0.05) in rats treated by DMP-1 compared with STZ group; 2) an apparent increment levels of NOS (p < 0.05), CAT (p < 0.05) and T-AOC (p < 0.05), while reduction in level of MDA (p < 0.05) in DMP-1 groups compared with STZ group; 3) a significant inhibition of TGF-β and Smad2/3 overexpression in kidney tissue. Here, SMAD2 is linked to diabetic kidney disease.