Plasma antioxidants and type 2 diabetes mellitus.

Reports indicate that some complications of diabetes mellitus are associated with increased activity of free radicals and accumulation of lipid peroxidation products. The organism's susceptibility to free radical stress and peroxidative damage is related to the balance between the free radical load and the adequacy of antioxidant defenses. In the present study, the relationship between plasma oxidants and antioxidants in diabetes mellitus was investigated. Thirty patients with type-2 diabetes mellitus were examined as well as twenty healthy controls (matched for age and sex against the diabetic patients). The plasma insulin and C-peptide levels in the diabetic group were significantly lower (p < 0.001) than that of the control group. The mean plasma fructosamine, lipid peroxide, lipids and low-density lipoprotein cholesterol (LDL-C) levels were significantly high (p < 0.001) in the diabetic group compared to the control group. There were not any significant differences in the plasma high-density lipoprotein cholesterol (HDL-C) levels between the patients and the control group (p < 0.001). The type-2 diabetes mellitus patients exhibited higher activities of plasma superoxide dismutase (SOD) than control values, whereas plasma glutathione peroxidase (GPx) activities were significantly lower. Our results suggest that there seems to be an imbalance between plasma oxidant and antioxidant systems in patients with type-2 diabetes mellitus. The estimation of plasma antioxidant levels and their replenishment by exogenous agents when necessary may be useful in the prevention of the diabetic complications.