Correlation of various serum biomarkers with the severity of diabetic retinopathy

Hyperglycemia induced inflammation and angiogenic factors are implicated as a contributor to the onset and progression of diabetic retinopathy (DR) in type 2 diabetes mellitus patients (T2DM). Tumor necrosis factor (TNF-alpha) and C-reactive protein (CRP) are inflammatory cytokines which induce retinal VEGF and are involved in the progression of proliferative diabetic retinopathy (PDR). Therefore the aim of the present study is to investigate the relationship between diabetic retinopathy and systemic inflammation in patients with type 2 diabetes mellitus. Patients with T2DM, with or without diabetic retinopathy were included in the study. Serum inflammatory cytokines, vascular growth factor were studied in different stages of DR. Patients with T2DM with and without diabetic retinopathy were compared. Patients with diabetic retinopathy had increased serum levels of inflammatory cytokines CRP, TNF-alpha, as well as VEGF compared to serum levels of diabetic patients without retinopathy. T2DM patients with retinopathy have higher levels of circulating inflammatory cytokines and VEGF compared to patients without retinopathy. These proinflammatory cytokines and angiogenic factors are involved in the progression of DR and proliferative diabetic retinopathy. The results showed the importance of inflammation and vascular endothelial growth factor in the progression of NPDR and PDR.