Serum Oxidized LDL Levels in Type 2 Diabetic Patients with Retinopathy in Mthatha Region of the Eastern Cape Province of South Africa

Oxidized low-density lipoprotein (ox-LDL) is a powerful natural prooxidant derived from native LDL by cell-mediated oxidation. Such oxidation occurs more easily in glycated LDL as observed in diabetes mellitus. We evaluated and compared selected biomarkers of oxidative stress and total antioxidant (TAO) levels in type 2 diabetes mellitus (T2DM) patients with and without retinopathy in the Mthatha region of the Eastern Cape Province, South Africa. The participants totaled to 140 and this number comprised 98 diabetic patients on treatment, stratified by diabetes (54) and diabetes with retinopathy (44). Forty-two nondiabetic healthy controls made up the 140. Fasting plasma glucose (FPG), glycosylated hemoglobin (HbA1c), lipid profile, serum ox-LDL, thiobarbituric acid reactive substances (TBARS), and TAO levels were measured. A statistically significant increase in FPG, HbA1c, TBARS, and ox-LDL and a significant decrease in TAO levels were seen in T2DM patients with retinopathy as compared to controls. A significant negative correlation was observed between TAO and ox-LDL levels in the diabetic group. In multiple linear regression analyses, duration of diabetes, triglyceride, TAO, and LDL cholesterol were found to be significantly associated with ox-LDL. In multiple logistic regression analyses, ox-LDL [OR 1.02 (1.01-1.03), P = 0.005] was the only risk factor and was significantly associated with the presence of retinopathy.