Dyslipidemia-Induced Oxidative Stress and its Implications in Diabetic Retinopathy

Abstract

Background: Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes mellitus and a leading cause of preventable blindness worldwide. Dyslipidemia and oxidative stress have been implicated in the pathogenesis of DR by promoting endothelial dysfunction, inflammation, and retinal vascular damage. The present study aimed to evaluate the association between dyslipidemia, oxidative stress, and diabetic retinopathy in patients with type 2 diabetes mellitus.

Objectives: To assess lipid profile abnormalities and oxidative stress markers in patients with type 2 diabetes mellitus with and without diabetic retinopathy and to determine their association with the development of diabetic retinopathy.

Materials and Methods: A hospital-based case-control study was conducted on 100 participants aged 30–65 years, including 50 patients with type 2 diabetes mellitus and diabetic retinopathy (cases) and 50 patients with type 2 diabetes mellitus without diabetic retinopathy (controls). Fasting blood glucose (FBG), postprandial blood glucose (PPBG), glycated hemoglobin (HbA1c), lipid profile [total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and very low-density lipoprotein cholesterol (VLDL-C)], malondialdehyde (MDA), and superoxide dismutase (SOD) were estimated using standard laboratory methods. Statistical analysis was performed using Student's t-test and Pearson's correlation coefficient. A p-value <0.05 was considered statistically significant.

Results: The mean age of the cases was significantly higher than that of the controls (57.66 ± 6.07 vs. 45.00 ± 8.01 years, p<0.0001). Patients with diabetic retinopathy exhibited significantly higher fasting blood glucose (180.08 ± 35.24 vs. 114.54 ± 28.57 mg/dL), postprandial blood glucose (248.16 ± 63.08 vs. 167.16 ± 24.37 mg/dL), and HbA1c (9.09 ± 2.35 vs. 5.66 ± 0.38%; p<0.0001 for all). Triglycerides (225.48 ± 144.69 vs. 155.04 ± 60.27 mg/dL; p=0.002) and VLDL-C (45.54 ± 18.11 vs. 34.70 ± 18.22 mg/dL; p=0.0036) were significantly elevated, whereas HDL-C was significantly reduced (38.14 ± 11.94 vs. 48.98 ± 12.11 mg/dL; p<0.0001) in cases. Total cholesterol and LDL-C did not differ significantly between the groups. Serum MDA levels were significantly higher in cases (3.81 ± 0.83 vs. 2.50 ± 1.35; p<0.0001), indicating increased oxidative stress, while SOD activity also differed significantly between the groups (179.72 ± 54.21 vs. 152.18 ± 52.96; p=0.0117). A strong positive correlation between MDA and SOD was observed in controls (r=0.610, p<0.001), whereas the correlation in cases was weak and not statistically significant (r=0.262, p=0.664).

Conclusion: Patients with diabetic retinopathy demonstrated significant dyslipidemia characterized by elevated triglycerides and VLDL-C, reduced HDL-C, poor glycemic control, and increased oxidative stress. These findings suggest that dyslipidemia-induced oxidative stress plays an important role in the pathogenesis of diabetic retinopathy. Early monitoring and management of lipid abnormalities and oxidative stress may help reduce the risk and progression of diabetic retinopathy in patients with type 2 diabetes mellitus.