Diabetic Retinopathy: Role of Oxidative Stress and Antioxidant Defence System

Aims: To estimate the oxidant/antioxidant status in type 2 diabetic patients with retinopathy; and to
correlate a number of independent variables (age, gender, education, body mass index, duration of
diabetes, glycosylated haemoglobin, hypertension) to development of retinopathy.
Study Design: Case-control study.
Place and Duration of Study: Research laboratories, Department of Medical Laboratories, College
of Applied Medical Sciences, Qassim University from April 2010 to April 2011.
Methodology: One-hundred diabetic patients with retinopathy recruited from King Fahad Specialist
Hospital- Buraidah were included in the study. The control groups were: control group 1 consisted of
sixty type 2 diabetic patients without retinopathy recruited from Diabetes and Endocrinology Center,
KFSH, Buraidah, KSA; and control group 2 consisted of sixty healthy "non diabetic subjects" recruited
from public places, i.e. Estarahes (party lounges). Plasma, serum, and erythrocyte lysate were
prepared from blood of each subject. Human serum 8-OHdG, plasma MDA, and erythrocyte lysate
Cu-Zn SOD were estimated by using commercial kits supplied by Northwest, U.S.A. Data was
analyzed using SPSS software and Win Episcope software. P-values < 0.05 were considered
significant.
Results: Age, education, duration of diabetes, poor glycaemic control, and hypertension were
consistently associated with development of retinopathy (OR 5.891, 4.44, 10.420, 1.699, 1.820
respectively). Moreover, increased plasma MDA, increased serum 8-OHdG levels, decreased Cu-Zn
SOD activity were observed in diabetic patients with retinopathy compared to subjects in control
groups. In addition, negative correlations were found between plasma MDA and Cu-Zn SOD activity,
HbA1c & Cu-Zn SOD activity as well in all subjects.
Conclusion: This report emphasizes the important role of oxidative stress in the development of
retinopathy in type 2 diabetes suggesting that blocking of oxidative stress is a crucial step for delayed
progression of diabetic retinopathy and hence the need for antioxidant supplements to postpone the
severity of diabetic retinopathy.