Oxidative stress is hypothesized to play a role in the development of diabetes with and without nephropathy. In addition, it has been suggested that some metabolic abormalities associated with diabetes may be due to cytokine overproduction. In the light of this knowledge, we aimed to measure MDA levels as a marker of oxidative stress and the IL-6 level in diabetes with and without different stages of nephropathy. Plasma MDA levels in the group of NIDDM patients with advanced nephropathy were significantly higher than in the group of NIDDM patients without nephropathy, which had significantly higher levels compared with the control group. Although IL-6 levels were elevated in diabetic groups with and without nephropathy in comparison with the control, no significant difference was found between patient groups. As a conclusion, oxidative stress may play an important role in diabetes with and without nephropathy, but the IL-6 level may not be useful in the evaluation of diabetic nephropathy.