A Randomised Trial Assessing the Synergistic Effects of Antidiabetic Pharmacotherapy and Dietary Intervention on Retinopathy Progression and Visual Function

Background Diabetic retinopathy (DR) is one of the most prevalent microvascular complications of diabetes, leading to progressive vision loss. Although pharmacotherapy can effectively control glycaemia, adjunctive nutritional strategies may enhance therapeutic outcomes by mitigating oxidative stress and inflammatory damage in retinal tissues. Objective To evaluate whether combining antidiabetic pharmacotherapy with a structured dietary intervention produces a synergistic effect on retinopathy progression and visual function among adults with type 2 diabetes. Design A 12-month, single-centre, randomised, open-label, parallel-group clinical trial. Participants / Materials Six hundred adults (aged 40–70 years) with non-proliferative diabetic retinopathy (NPDR) attending Asim Eye Care Clinic, Delhi-NCR, were enrolled. Participants were randomly allocated (1:1) to pharmacotherapy-only (control) or pharmacotherapy + dietary intervention (intervention) groups. Intervention Both groups received standardised pharmacotherapy (metformin ± insulin, as clinically indicated). The intervention group additionally followed a supervised diet plan rich in low-glycaemic carbohydrates, omega-3 fatty acids, lutein, zeaxanthin, vitamins C and E, and zinc. Nutritionists reviewed compliance every two weeks. Outcomes Primary: change in Early Treatment Diabetic Retinopathy Study (ETDRS) grading. Secondary: best-corrected visual acuity (BCVA), serum HbA1c, fasting glucose, inflammatory biomarkers (CRP, IL-6), and retinal thickness via OCT. Results After 12 months, retinopathy progression was significantly lower in the combined-therapy group (7.6 %) than in controls (18.3 %, p < 0.01). BCVA improved by +0.08 logMAR (95 % CI 0.06–0.10) vs –0.02 logMAR in controls. Mean HbA1c decreased by 1.4 ± 0.3 % compared with 0.7 ± 0.4 % (p < 0.001). Inflammatory markers reduced significantly in the diet group, correlating with retinal structural stability. Conclusions Adjunctive dietary intervention enhances the effectiveness of antidiabetic pharmacotherapy, delaying DR progression and improving visual outcomes. Integrating targeted nutrition should be considered a core component of diabetes-retinopathy management.