Retinol-binding protein 3 (RBP3) is a retinol transporter protein secreted by photoreceptors, and high levels of RBP3 in the vitreous body of patients with diabetes slow DR progression.209 Elevated RBP3 expression can alleviate hyperglycemia-induced DR by inhibiting glucose uptake by glucose transporter protein-1 and reducing the expression of inflammatory cytokines and VEGF.210 Therefore, RBP3 could serve as a biomarker and therapeutic strategy in preventing the progression of DR. This evidence concerns the gene RBP3 and diabetes mellitus.