Background: Diabetic neuropathy is the most prevalent complication of diabetes mellitus, affecting up to 50% of patients with type 2 diabetes mellitus (T2DM). Among the various types of diabetic neuropathy, diabetic peripheral neuropathy (DPN) is the most common. Numerous animal studies have highlighted a strong association between the improvement of DPN and curcumin supplementation, particularly due to curcumin's anti-inflammatory and antioxidant properties. However, the effects of curcumin on DPN have been evaluated in only one randomized controlled trial. In our study, we assessed the efficacy and safety of a 16-week supplementation with nanocurcumin in T2DM patients suffering from DPN.

Methods: This randomized, double-blind, placebo-controlled trial was conducted at a diabetes clinic within the Endocrinology and Metabolism Research Center in Tehran, Iran. The study aimed to evaluate the effects of nanocurcumin (40 mg taken twice daily) compared to a placebo in patients with DPN over a 16-week period. The primary endpoint of the study was the reduction of pain severity, measured by the Numerical Rating Scale (NRS). Additionally, we assessed neuropathic outcomes by monitoring changes in the Michigan Neuropathy Screening Instrument examination (MNSIE) and the Neuropathy Disability Score (NDS). Secondary endpoints included improvements in metabolic and cardiovascular parameters from baseline to the end of the treatment.

Results: Ninety-seven patients were randomized, with 41 in the nanocurcumin group and 45 in the placebo group completing the study. No significant differences were found between the groups in terms of NRS (P = 0.787), NDS (P = 0.576), or MNSIE (P = 0.405) after 16 weeks. Nanocurcumin supplementation did not alter the metabolic profile or cardiovascular parameters and was well-tolerated, without major adverse events.

Conclusion: Nanocurcumin supplementation over 16 weeks did not improve pain, neuropathic outcomes, or metabolic/cardiovascular parameters in patients with T2DM suffering from DPN.