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

Background: 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.

Materials and methods: 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) (n = 30) or (ii) the matched placebo (n = 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.

Results: 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; P = 0.022) and superoxide dismutases (0.77 ± 2.11 vs. -0.45 ± 3.08; P = 0.031), while it decreased and malondialdehyde (MDA) (-1.06 ± 5.80 vs. 1.89 ± 6.12; P = 0.043) and creatinine (-0.04 ± 0.16 vs. 0.03 ± 0.05; P = 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.

Conclusion: Curcumin-piperine is effective in improving oxidative stress and reducing creatinine in DR. Further trials are necessary to confirm these promising findings.