Short-term effects of oral curcumin as adjunct to intravitreal bevacizumab in diabetic macular edema: a randomized clinical trial

Abstract Purpose To evaluate the efficacy of combined oral curcumin and intravitreal bevacizumab (IVB) in diabetic macular edema (DME). Methods This clinical trial was conducted using a parallel-group, randomized, placebo-controlled design in patients with DME. All participants received IVB at the standard dose at monthly intervals for a total of three doses. Additionally, they were assigned to receive either oral curcumin capsules (40 mg) or a matched placebo every 12 h for three months, starting at the time of the first IVB injection. Treatment efficacy was assessed by comparing changes in foveal, perifoveal, and parafoveal retinal thickness, central macular volume (CMV), and LogMAR-corrected distance visual acuity (CDVA). Hemoglobin A1c (HbA1c) tests were performed for all patients at baseline and at three months. Results Fifty-two eyes of 52 patients (26 eyes per group) completed the study. The patients’ baseline characteristics were comparable between the groups. Macular thickness and CMV decreased significantly from baseline in both groups, with no statistically significant difference observed between the groups. Similarly, changes in LogMAR CDVA did not differ significantly between the intervention and control groups (MD: 0.08, [95% CI: -0.04 to 0.20]; P = 0.12). Both groups demonstrated a significant reduction in HbA1c levels at three months compared to baseline; however, the difference in HbA1c changes between the groups was statistically significant ( P < 0.001), favoring the curcumin group (MD: 0.63%, 95% CI: [0.3-1.0]). No specific systemic or ocular adverse effects were observed in either group during the study. Conclusion Adjunctive treatment with oral curcumin in patients receiving IVB for DME was associated with a significantly greater reduction in HbA1c levels. Despite this metabolic outcome, oral curcumin did not provide additional detectable anatomical or functional benefit over intravitreal bevacizumab alone during the three-month follow-up.