Coenzyme Q10 as a potential add-on treatment for patients suffering from painful diabetic neuropathy: results of a placebo-controlled randomized trial.

BACKGROUND: We hypothesized that the addition of coenzyme Q10 (CoQ10) to pregabalin might be helpful in improving symptoms in patients suffering from painful diabetic neuropathy (PDN). METHODS: One hundred twelve patients with PDN were randomly allocated to receive CoQ10 + pregabalin (57 patients) or placebo + pregabalin (55 patients). Besides pregabalin (150 mg/day), the patients, upon their group assignment, received CoQ10 at a dosage of 100 mg every 8 h or matched placebo for 8 consecutive weeks. The primary efficacy measure was the changes in the pain intensity from baseline to endpoint measured on an 11-point NRS (numeric rating scale). Secondary efficacy measures included the changes in the pain-associated sleep interference score (SIS) as well as the patients' global improvement with treatment measured on the Clinicians' and Patients' Global Impression of Change (CGIC/PGIC). RESULTS: On the intent­to­treat population (ITT) analysis, the CoQ10 + pregabalin regimen resulted in significantly greater pain relief than the placebo + pregabalin regimen. By the end of week 2, the decrease in the mean pain NRS score was similar in both groups, but at the end of weeks four and eight, the decrease in the mean pain NRS score was significantly greater in patients taking CoQ10 + pregabalin than in those taking placebo + pregabalin (p value = 0.01 and < 0.001, respectively). Likewise, at the end of week 8, the decrease in the pain-associated SIS was significantly greater in the patients supplemented with CoQ10 compared to placebo. Furthermore, the proportion of the responder patients (those having ≥ 50% decline in the mean pain NRS score) as well as the proportion of patients rated ''very much'' or ''much improved'' on the CGIC/PGIC scales were also significantly higher in the CoQ10 + pregabalin-treated patients than placebo + pregabalin-treated patients. CONCLUSIONS: Our data support the idea that diabetic patients suffering from PDN may benefit from using antioxidant and anti-inflammatory supplements like CoQ10. However, further studies are required before supplementation with CoQ10 can be recommended for treating PDN. TRIAL REGISTRATION: The trial was registered at Iranian Registry of Clinical Trials (identifier code: IRCT20120215009014N385). Registration date: 2021-02-21.