Oxidative Stress in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the micro-vascular complications of diabetes which leads to blindness among the working age individuals. Chronic hyperglycaemia and dyslipidaemia cause oxidative stress and increase the free radicals. Oxidative stress is one of the important causes in the genesis of microangiopathy. Twenty five patients of Type II Diabetes mellitus (DM) without retinopathy, 50 patients of Type II Diabetes mellitus with non-proliferative diabetic retinopathy and proliferative diabetic retinopathy and 25 normal subjects were included in the study. Fasting plasma glucose (FPG), post prandial plasma glucose (PPPG), glycosylated haemoglobin, lipid profile, plasma malondialdehyde (MDA) and Vitamin C were estimated. The plasma MDA levels were significantly elevated (p<0.001) and the Vitamin C levels were significantly decreased (p<0.01) as compared to the controls. The study revealed a significant positive association between plasma MDA and both FPG and PPPG (r=0.438, p<0.01, r=0.455, p<0.01), a positive correlation between plasma MDA and HbA1c and also, a positive correlation between plasma MDA and serum triglycerides (r=0.028, p<0.01, r=0.454, p<0.01) and a negative correlation between MDA and Vitamin C (r=0.241, p<0.01). The results suggest that increased lipid peroxidation and a decline in the antioxidant defense mechanisms plays a very important role in the initiation and progression of micro-vascular complications like diabetic retinopathy.