The Usefulness of Serum Sorbitol and Vascular Endothelial Growth Factor A in Predicting Diabetic Retinopathy as Compared to Optical Coherence Tomography

No specific and sufficient diagnostic biomarkers are currently available for predicting diabetic retinopathy (DR). This study was conducted to investigate the validity of serum sorbitol and Vascular Endothelial Growth Factor A (VEGF-A) in diagnosing DR and differentiating it from diabetes without retinopathy (DNR). The study also investigated the diagnostic efficiency of these biomarkers when compared to optical coherence tomography OCT. A cross-sectional study included 164 diabetes mellitus patients: 30 patients with no retinopathy (the control group), 86 patients with non-proliferative diabetic retinopathy (NPDR), and 48 patients with Proliferative Diabetic Retinopathy (PDR). Patients were referred to the Layla Qasim Diabetic Center between November 2016 and October 2017 and an ophthalmologist established a DR diagnosis using OCT. Serum sorbitol and serum VEGF-A were measured for all patients. By using study biomarkers, the cut-off values of VEGF-A (124.7 ng/ml) and sorbitol (0.3112 mg/ml) were established, and their validity parameters. For sorbitol, the values were as follows: specificity was 75.4, the sensitivity was 80 and 68.3% of observed agreement with the results of the OCT technique. For VEGF-A, the specificity was 73.1 the sensitivity was 80 and 76.2% of the observed agreement. The combined parallel test was applied as negative if both the tests were negative or as positive if either of the tests was positive: a highly significant statistical agreement (Kappa test p <0.001) was found with the gold standard diagnosis (OCT), with 85.4% of observed agreement. A combination of serum sorbitol and VEGF-A for diagnosing DR and for differentiating DR from DNR patients exhibits a significant agreement with an OCT diagnosis.