Difference in SOD activity between diabetic patients and healthy subjects is probably accountable not only by genotype background but also by various effects in terms of diabetes, e.g. enzyme glycation.The lower serum SOD activity was found in patients (T1DM and T2DM) with macrovascular complications (0,51 ± 0,31 U; 95%CI: 0,43, 0,58) than in those with microvascular complications (0,74 ± 0,16 U; 95%CI: 0,71, 0,76), p < 0,01 or without any vascular complications (0,76 ± 0,34 U;95%CI: 0,71, 0,81), p < 0,05. Here, SOD1 is linked to type 2 diabetes mellitus.