During the progression of DN, the antioxidant scavenging system does not work, accompanying by decreased activity and expression of antioxidase, including catalase (CAT), heme oxygenase (HO-1), NADPH: quinone acceptor oxidoreductase 1 (NQO1), superoxide dismutase (SOD) and glutathione peroxidase (GPx). This evidence concerns the gene CAT and liver dysplastic nodule.