The Impact of Glycemic Control on Ranibizumab Efficacy in Diabetic Retinopathy: A Retrospective Analysis.

Background:  Diabetic retinopathy (DR), a leading cause of vision loss, is driven by inflammation, oxidative stress, and vascular endothelial growth factor (VEGF) production, with elevated blood glucose and advanced glycation end products (AGEs) exacerbating retinal damage. While intravitreal VEGF inhibitors have become the first-line treatment for diabetic macular edema (DME), response to therapy varies due to systemic factors such as HbA1c levels, blood pressure, and diabetes duration.

Objectives: This study aims to assess the impact of glycosylated hemoglobin (HbA1c) control on the effectiveness of Ranibizumab treatment in patients with DR.

Methodology: The study included 222 eyes from 222 patients with type 2 diabetes, comprising 60% males and 40% females, with an average age of 60.2 ± 9.32 years. Participants were administered monthly intravitreal injections of Ranibizumab, 0.05 mL of a 6 mg/mL solution, over three months, and an optical coherence tomography (OCT) was done one month after the treatment for the evaluation of the patient's need for further injections. HbA1c, central retinal thickness (CRT), and best-corrected visual acuity (BCVA) were measured at the beginning and end of the study. Patients were then divided into two groups according to their HbA1c level, with a cut-off point of 7% (53 mmol/mol).

Results: At the beginning of the study, the HbA1c mean was 8.16% ± 1.2%, the BCVA mean was 59.7 ± 9.73, and the central macular thickness (CMT) mean was 465.4 ± 132.34 µm. Twelve months later, the 222 patients were separated into two groups based on HbA1c levels: 109 patients had an HbA1c >7% (group A) and 113 patients had an HbA1c ≤7% (group B). The improvement of BCVA was 6.1 ± 7.3 for group A versus 7.9 ± 6.1 for group B ( = 0.0478). The reduction in CMT was 164.2 ± 122.8 μm for group A versus 197.8 ± 125.1 μm for group B ( = 0.0447).

Conclusions: Our study indicates that HbA1c control influences the treatment outcomes of intravitreal Ranibizumab for DME, with better responses observed in patients whose HbA1c is below 7%.