This study was undertaken to evaluate the levels of plasma magnesium, lipid peroxides, nitric oxide end products, erythrocyte membrane lipid peroxides, erythrocyte reduced glutathione and erythrocyte superoxide dismutase activity in type-2 diabetes mellitus patients. 60 patients with type-2 diabetes mellitus and 30 healthy control subjects were included in this study. Among 60 type-2 diabetic patients, 30 patients were without complication and 30 patients were with various complications. Decreased levels of plasma magnesium, erythrocyte reduced glutathione and erythrocyte superoxide dismutase activity while increased levels of plasma lipid peroxides, nitric oxide end products and erythrocyte membrane lipid peroxides were observed in patients with type-2 diabetes mellitus. We propose that, under the shadow of hypomagnesaemia, there is excessive production of reactive oxygen species and reactive nitrogen species as reflected by elevated lipid peroxides and nitric oxide end products concomitant with dwindled antioxidants and suggest their association with late complications in type-2 diabetes mellitus.