Vitreous and Serum Levels of Apelin in Type 2 Diabetic Patients with Diabetic Retinopathy

Background: Diabetic retinopathy (DR) is the most common microvascular complication of diabetes, and is the leading cause of blindness and visual impairment in the working-age population. Retinal neovascularization is the most important clinical features of proliferative DR (PDR). Apelin is an endogenous ligand of the G proteincoupled receptor, which has been shown to be involved in retinal angiogenesis. Objective: To study vitreous and serum levels of apelin in type 2 diabetic patients with diabetic retinopathy. Patients and methods: Case control study was conducted on total 60 subjects, 40 type 2 diabetic patients and 20 non diabetic subjects as control group. Diabetic patients were divided into 2 groups. Results: Serum and vitreous levels of apelin were significantly higher in patients with PDR compared to NPDR and control group (P< 0.001). There was non-significant correlation between serum and vitreous apelin. Serum apelin showed lower cut off value (>4.45 ng/ml (P<0.001) with 96.7% sensitivity and 96.7 specificity) for detection of PDR compared to control group than vitreous apelin. Also serum apelin showed lower cut off value >3.55 ng/ml for detection of NPDR compared to control group. Conclusion: Elevation of serum apelin in patients with PDR compared to NPDR and control group suggesting the role of apelin in development of retinal neovascularization and diabetic retinopathy. So antagonizing effect of apelin can be used as targeted therapy for treatment of diabetic retinopathy. We can rely on serum apelin for early detection of diabetic retinopathy than vitreous apelin.