The present study was designed to use high-performance liquid chromatography (HPLC), methylation-specific polymerase chain reaction (MSP) and bisulfite sequencing (BS) to investigate the methylation levels of the whole genome and the CTGF promoter in patients with type 2 DM, and to analyze the possible correlation with serum CTGF expression and the pathogenesis of nephropathy. The gene discussed is CCN2; the disease is kidney disorder.