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Serum total superoxide dismutase enzyme activity in type 2 diabetic patients with retinopathy in Mthatha region of the Eastern Cape Province of South Africa

Superoxide dismutase is an important antioxidant enzyme and plays an important role against oxidative stress by catalyzing dismutation of superoxide radical. The aim of the present study was to evaluate total superoxide dismutase enzyme activity and total antioxidant levels in type 2 diabetic patients with retinopathy in the region and to compare it with that of type 2 diabetics without retinopathy and healthy non-diabetic controls. 140 participants were recruited with their consent and divided into three groups (44 with type 2 diabetics with retinopathy, 54 type 2 diabetics without retinopathy and 42 healthy nondiabetic controls). Fasting plasma glucose (FPG) and glycosylated hemoglobin were assayed by routine laboratory methods. Serum total superoxide dismutase (SOD) enzyme activity and total antioxidant (TAO) levels were measured using standard commercial reagent kits. The results are expressed as mean ± SD and median (IQR). There was statistically significant increase seen in FPG, HbA1c, and SOD enzyme activity in type 2 diabetic patients with and without retinopathy as compared to control population, whereas total antioxidant levels was significantly decreased in diabetic patients. Significant negative correlation was seen between TAO and SOD enzyme activity in diabetic group. SOD and duration of disease were found to be significantly associated with the presence of retinopathy in multiple logistic analyses. Present study strongly suggests the role of oxidative stress in the pathophysiology of diabetic retinopathy as is evident by the increased SOD activity and the decreased total antioxidant levels, thus making SOD a probable oxidative stress biomarker.

Author(s): Ganjifrockwala FA, Joseph JT, George G