Influence of Vitamin E Supplementation on Glycaemic Control: A Meta-Analysis of Randomised Controlled Trials

Abstract

Observational studies have revealed that higher serum vitamin E concentrations and increased vitamin E intake and vitamin E supplementation are associated with beneficial effects on glycaemic control in type 2 diabetes mellitus (T2DM). However, whether vitamin E supplementation exerts a definitive effect on glycaemic control remains unclear. This article involves a meta-analysis of randomised controlled trials of vitamin E to better characterise its impact on HbA1c, fasting glucose and fasting insulin. PubMed, EMBASE and the Cochrane Library were electronically searched from the earliest possible date through April 2013 for all relevant studies. Weighted mean difference (WMD) was calculated for net changes using fixed-effects or random-effects models. Standard methods for assessing statistical heterogeneity and publication bias were used. Fourteen randomised controlled trials involving individual data on 714 subjects were collected in this meta-analysis. Increased vitamin E supplementation did not result in significant benefits in glycaemic control as measured by reductions in HbA1c, fasting glucose and fasting insulin. Subgroup analyses revealed a significant reduction in HbA1c (−0.58%, 95% CI −0.83 to −0.34) and fasting insulin (−9.0 pmol/l, 95% CI −15.90 to −2.10) compared with controls in patients with low baseline vitamin E status. Subgroup analyses also demonstrated that the outcomes may have been influenced by the vitamin E dosage, study duration, ethnic group, serum HbA1c concentration, and fasting glucose control status. In conclusion, there is currently insufficient evidence to support a potential beneficial effect of vitamin E supplementation on improvements of HbA1c and fasting glucose and insulin concentrations in subjects with T2DM.

Influence of Ascorbic Acid Supplementation on Type 2 Diabetes Mellitus in Observational and Randomized Controlled Trials; A Systematic Review with Meta-Analysis

“…We could not see the beneficial effects of other antioxidants; eicosapentaenoic acid (59), or VE (63,65) with/without AA on FBS, this finding was similar to results obtained by previous metaanalysis in diabetics (13,101).…”

“…Several epidemiological studies have shown that individuals with low concentration of antioxidants are at increased risk of diabetes complications (8,9). Recently, Xu et al (13) published the effect of vitamin E (VE) supplementation on diabetes improvement. Along with their work, we aimed to critically and systematically, assess the effect of ascorbic acid (AA) in diabetes.…”

HbA1c: a review of non-glycaemic variables

“…However, interstudy heterogeneity led to further subgroup analysis, which revealed a significant reduction in HbA1c in hypovitaminosis E T2DM patients following supplementation 89. However, as noted by the authors, the small datasets involved in this subgroup analysis mean further studies are required to corroborate this finding before any recommendations can be made.…”

Clinical and Vitamin Response to a Short‐Term Multi‐Micronutrient Intervention in Brazilian Children and Teens: From Population Data to Interindividual Responses

“…Vitamin E intake may reduce glucose levels in type 2 diabetics and in subjects with baseline serum vitamin E deficiencies . High doses of vitamin E (>400 IU d –1 ) supplemented for longer periods (>12 weeks) significantly reduced HbA1c levels and fasting insulinemia …”