SOD3 and type 2 diabetes mellitus: By multivariate logistic regression analysis, duration of T2DM (OR = 1.076, P = 0.004), SBP (OR = 1.029, P = 0.017), HbA1c (OR = 1.241, P = 0.024), and serum ecSOD activity (OR = 0.920, P < 0.001) were the independent and significant risk factors of DR in T2DM patients (Figure 2).