Superoxide Dismutase and Glutathione Peroxidase Levels in Patients with Long Standing Type 2 Diabetes in Port Harcourt, Rivers State, Nigeria

Diabetes mellitus (DM) is a group of metabolic diseases characterized by hyperglycaemia resulting from defects in insulin secretion, insulin action, or both. It is associated with increased oxidative stress. This study evaluates the levels of the antioxidant enzymes superoxide dismutase (SOD) and gluthathione peroxidase (GPx), as a measure of antioxidant status in Type 2 diabetics. A total of 182 subjects were involved in the study, of which 109 were diabetics (Test) and 73 non-diabetics (Controls). The criterion for the classification as a diabetic was based on subjects having glycated haemoglobin (HbA1c) levels ≥ 6.5%. A structured interviewer administered questionnaire was used as an aid in the collection of demographic and lifestyle data from the subjects. HbA1c was estimated quantitatively by immunochemical method. SOD and GPx was measured by the sandwich-enzyme linked immunosorbent assay (ELISA) method. Glucose oxidase method was used for the determination of fasting plasma glucose (FPG). Mean SOD and GPx values in the diabetic subjects were significantly lower (p<0.05) as compared with that of the controls. Also, there were significant decreases (p<0.05) in the levels of the enzymes with increasing years of illness. There were no significant differences (p>0.05) in the levels of SOD and GPx in diabetic subjects with respect to age differences, even though the enzyme levels decreased with increasing age. FPG and HbA1c levels were significantly higher (p<0.05) in the diabetics as compared to the controls. Type 2 diabetes is associated with decreased antioxidative status as the levels of the antioxidant enzymes SOD and GPx were significantly reduced in the diabetic subjects. The increasing duration of the illness further depresses the antioxidative system. As the disease condition progresses, antioxidative parameters are further depleted, showing an increase in oxidative stress. It is thus recommended that antioxidative therapy be incorporated in the management/therapy of Type 2 diabetics, to supplement the endogenous anti-oxidative system, as this could prevent or delay progression of the disease and the development of late diabetic complications.