Folic acid supplementation on inflammation and homocysteine in type 2 diabetes mellitus: systematic review and meta-analysis of randomized controlled trials

Abstract

Background The beneficial effects of folate have been observed under different conditions, but the available evidence on inflammation and reduction of cardiovascular disease (CVD) in type 2 diabetes mellitus (T2DM) is limited. The study aimed to explore the effects of folate on inflammation and homocysteine amongst individuals with T2DM. Methods PubMed, Scopus, and Cochrane Library were used to search for evidence. A random-effect model meta-analysis through Review Manager (version 5.4) and metaHun was performed. Results were reported as standardized mean differences (SMD) and 95% confidence intervals graphically using forest and funnel plots. Results Data from 9 trials with 426 patients living with T2DM were analyzed. Folic acid supplementation significantly revealed a large effect size on homocysteine levels compared to placebo, SMD = −1.53, 95%CI (−2.14,−0.93), p < 0.05. Additionally, we observed a medium marginal effect size on C-reactive protein (SMD = −0.68, 95%CI (−1.34, −0.01), p = 0.05). However, no significant effect on tumor necrosis factor-α (SMD = −0.86, 95%CI (−2.65, 0.93), p = 0.34), and interleukin-6 (SMD = −0.04, 95%CI (−1.08, 1.01), p = 0.95) was observed. Conclusion Evidence analyzed in this study suggests that folic acid supplementation in T2DM reduces homocysteine and may mitigate CVDs. However, its effect on inflammation is inconclusive.