Malondialdehyde, glutathione, glutathione peroxidase and homocysteine levels in type 2 diabetic patients with and without microalbuminuria

Abstract

High levels of homocysteine and oxidative stress are known to be associated with premature vascular disease in type 2 diabetes mellitus (DM). The aim of this study was to estimate homocysteine levels and oxidant-antioxidant status and to determine the relationship between them in type 2 diabetic patients with and without microalbuminuria. Fasting blood samples were obtained from 48 diabetic patients (17 with and 31 without microalbuminuria) and 20 healthy subjects. Serum total homocysteine (tHcy), plasma malondialdehyde (MDA) erythrocyte glutathione (GSH) and glutathione peroxidase (GPx) activity were measured in these patients and the results were compared with those of controls who were chosen among healthy subjects. MDA levels were found to be significantly lower and GSH levels and GPx activities were found to be significantly higher in control subjects when compared with patients with and without microalbuminuria (MDA: P < 0.0001, P < 0.0001; GSH: P < 0.0001, P < 0.0001; GPx: P < 0.0001, P < 0.001, respectively). MDA levels were found to be significantly higher in patients with microalbuminuria compared with patients without microalbuminuria (P < 0.0001), while similarly GSH levels were found to be significantly lower in patients with microalbuminuria (P < 0.0001). Although there were no significant differences with respect to tHcy levels and GPx activities between the microalbuminuric and normoalbuminuric patients (P > 0.05), there was a significant difference with respect to tHcy levels between healthy controls and patients with microalbuminuria (P < 0.05). The serum levels of tHcy correlated best with plasma MDA and erythrocyte GSH concentrations in all diabetic patients (r = 0.549, P < 0.0001; r = -0.385, P<0.01). Decreased antioxidant levels, increased lipid peroxidation and increased tHcy levels were observed in patients with microalbuminuria. These changes may contribute to vascular disease, which is particularly prevalent in type 2 DM patients with microalbuminuria.