Effects of coenzyme Q(10) supplementation on metabolic profile in diabetes: a systematic review and meta-analysis

What is known and objectiveCoenzymeQ(10) (CoQ(10)), or ubiquinone, is an endogenous enzyme cofactor produced by most human cells. It is a potent antioxidant and is necessary for energy production in mitochondria. Diabetes mellitus is a chronic disease with multiple metabolic abnormalities, principally resulting from the inflammation and oxidative stress associated with mitochondrial dysfunctions. Clinical trials of the effects of supplementary CoQ(10) on metabolic control in diabetes have reported inconsistent results. We undertook a systematic review and meta-analysis of randomized controlled trials to assess the effects of CoQ(10) supplementation on glycaemic control, lipid profile and blood pressure in patients with diabetes. MethodsA systematic search was conducted on MEDLINE, The Cochrane Library, CINAHL, NCCAM, Web of Science, Scopus, ClinicalTrials.gov and historical search of reference lists of relevant articles. The bibliographic databases were searched from inception to February 2015. We included randomized, placebo-controlled trials of CoQ(10) in diabetes lasting at least 12weeks. HbA(1c) or fasting plasma glucose had to be reported. Primary outcome was glycemic control, and secondary outcomes were lipid profile and blood pressure. Treatment effect was estimated with mean difference. Results and discussionSeven trials were included in the meta-analysis, involving 356 patients. Neither CoQ(10) alone nor CoQ(10) plus fenofibrate improved glycemic control. In addition, CoQ10, alone or in combination with fenofibrate, did not alter LDL-C, HDL-C and blood pressure. Triglycerides levels were significantly reduced with CoQ(10) (mean difference -026mmol/L, 95% CI -005mmol/L to -047mmol/L, P=002) and CoQ(10) plus fenofibrate (mean difference -072mmol/L, 95% CI -032mmol/L to -112mmol/L, P=00004). CoQ(10) plus fenofibrate also effectively reduced total cholesterol (mean difference: -045mmol/L, 95% CI -006mmol/L to -084mmol/L, P=002). What is new and conclusionsCoQ(10) supplementation has no beneficial effects on glycemic control, lipid profile or blood pressure in patients with diabetes. However, it may reduce triglycerides levels. Due to limited data availability, well-powered and well-designed randomized controlled trials are needed to clearly determine the effect of CoQ(10) on metabolic profile in diabetes. Dosage effects should also be explored.