In order to exclude the confounding variables affecting the serum CTGF levels in patients with type 2 DM and DN, Pearson’s correlation analysis was used, and the results showed that age (r=0.197, P<0.05), UACR (r=0.591, P<0.01), BUN (r=0.443, P<0.01), Cr (r=0.393, P<0.01), FBS (r=0.278, P<0.01) and PBS (r=0.399, P<0.01) were positively correlated with CTGF expression levels, while a significant negative correlation was detected for the eGFR (r=−0.438, P<0.01), methylation levels (r=−0.367, P<0.01) and CTGF expression levels. This evidence concerns the gene CCN2 and liver dysplastic nodule.