The efficacy of curcumin-piperine supplementation in patients with nonproliferative diabetic retinopathy: An optical coherence tomography angiography-based randomized controlled trial

Diabetic retinopathy (DR) is one of the complications of diabetes. This study was conducted to investigate the effect of curcumin-piperine on laboratory factors and macular vascular in DR. The present study was a randomized, placebo-controlled, double-blind, parallel-arm clinical trial that was conducted on 60 patients with DR aged 30-65 years. Patients were randomized into two groups to receive (i) 1010 mg/day of curcumin-piperine (two tablets per day, each tablet containing 500 mg curcuminoids and 5 mg piperine) ( = 30) or (ii) the matched placebo ( = 30) for 12 weeks. The investigated factors included optical coherence tomography (OCT), optical coherence tomography angiography (OCTA), oxidative stress factors, C-reactive protein (CRP), fasting blood glucose (FBG), triglycerides (TGs), blood urea nitrogen (BUN), and creatinine. The trial was completed by 27 patients in the intervention group and 29 patients in the placebo group. Curcumin-piperine significantly increased total antioxidant capacity (0.86 ± 0.66 vs. 0.45 ± 0.89; = 0.022) and superoxide dismutases (0.77 ± 2.11 vs. -0.45 ± 3.08; = 0.031), while it decreased and malondialdehyde (MDA) (-1.06 ± 5.80 vs. 1.89 ± 6.12; = 0.043) and creatinine (-0.04 ± 0.16 vs. 0.03 ± 0.05; = 0.042) compared with placebo. However, this supplement had no significant effect on CRP, FBG, TG, BUN, OCT, and OCTA. There were no adverse reactions. Curcumin-piperine is effective in improving oxidative stress and reducing creatinine in DR. Further trials are necessary to confirm these promising findings.