Serum markers of oxidative stress and severity of diabetic retinopathy

OBJECTIVE - To compare serum markers of oxidative stress with diabetic reti nopathy seventy. RESEARCH DESIGN AND METHODS - This cross-sectional study compared patients with types 1 and 2 diabetes with control subjects in western New York and P ennsylvania. Retinopathy severity was graded from funduscopic fields based on the Early Treatment of Diabetic Retinopathy Study Serum samples were ana lyzed for thiobarbituric acid-reacting substances (TBARS), superoxide dismu tase (SOD) and glutathione peroxidase (GSH-Px) activities, creatinine, HbA( 1), and triglycerides. Appropriate analysis of covariance models were perfo rmed. RESULTS- TBARS (P = 0.019), triglyceride (P = 0.004), and glucose and HbA(1 ) (both P < 0.001) levels were elevated in diabetic patients compared with those in control subjects. SOD (P = 0.003) and GSH-Px (P = 0.046) levels we re lower in diabetic patients than in control subjects, No correlation exis ted between SOD levels and either glucose or HbA(1), levels. No significant associations existed between levels of TEARS, SOD, or GSH-Px an severity o f diabetic retinopathy There was a significant association between poorer v isual acuity and worse retinopathy (P = 0.009), which was only partly expla ined by macular edema. CONCLUSIONS - increased levels of TEARS and decreased levels of SOD and GSH -Px were found in diabetic patients compared with those in control subjects , but no significant associations were found between the levels of these su bstances and severity of retinopathy. When duration and type of diabetes an d serum HbA(1) levels were taken into account, only visual acuity remained associated with more severe retinopathy.