Diabetic retinopathy (DR) is a sight-threatening complication of diabetes mellitus (DM). Oxidative stress generated on account of hyperglycemic state may lead to retinal abnormalities including DR.
To evaluate the status of antioxidant enzymes -superoxide dismutase (SOD) and catalase (CAT); with different stages of DR severity in subjects with type 1 and type 2 DM.
The cross-sectional study enrolled 148 subjects with type 1 DM (n=17); type 2 DM (n=96) and non-diabetes controls (n=35). Subjects with DM were divided into two subgroups based on DR severity (mild-to-severe non-proliferative DR and proliferative DR [PDR]) and Serum glycated hemoglobin (HbA1c), lipid profile, SOD and CAT were estimated.
Both SOD and CAT levels were lower in diabetes subjects than non-diabetic controls. A significant positive correlation was found between HbA1C level and severity of DR (P<0.0001). Levels of SOD and CAT varied significantly with DR severity in both diabetic groups at p<0.05. Furthermore, levels of SOD and CAT was found to decrease significantly (P<0.001) in DR (+) compared to DR (-) patients. Also, increased levels of HbA1c was significantly associated (P<0.001) with decreased SOD in both subgroups (NPDR and PDR). DR severity was significantly associated with SOD and CAT in the NPDR and PDR subgroups (P<0.05).
Oxidative stress and decreased antioxidant defenses are associated with DR progression to its PDR stage.