Serum Retinol-binding Protein 3 as a Potential Biomarker for Diabetic Retinopathy Severity: A Cross-sectional Study

Introduction: Diabetic Retinopathy (DR) is one of the leading causes of visual impairment worldwide. Its progression is influenced by complex metabolic, inflammatory and neurodegenerative mechanisms. Retinol-binding Protein 3 (RBP3), a retina-specific glycoprotein essential for the visual cycle, has recently gained attention due to its potential neuroprotective and anti-inflammatory roles. Reduced RBP3 levels may contribute to retinal dysfunction, making it a possible biomarker for DR risk stratification. Aim: To assess serum RBP3 levels among Type 2 Diabetes Mellitus (T2DM) patients and determine its association with the severity of DR, glycaemic control and systemic inflammation. Materials and Methods: A hospital-based cross-sectional study was conducted at Nootan Medical College and Research Centre, Visnagar, Gujarat, India, from January 2023 to February 2024, in collaboration with the Departments of Biochemistry, Ophthalmology, and Medicine. A total of 100 T2DM patients (aged 45-65 years) were enrolled. Detailed retinal examinations were performed to classify DR severity. Serum RBP3 levels were measured using Enzyme-Linked Immunosorbent Assay (ELISA). Glycated Haemoglobin (HbA1c) and high-sensitivity C-Reactive Protein (hs-CRP) were evaluated as indicators of glycaemic status and systemic inflammation. Statistical analysis was performed using MedCalc software, with p-value