The effect of cinnamon supplementation on glycemic control in women with polycystic ovary syndrome: A systematic review and meta-analysis

Several clinical trials have identified glycemic-lowering effects of cinnamon, while other studies have reported conflicting findings. A comprehensive systematic search on Embase, PubMed, Scopus, Web of Science, and Cochrane Library was conducted using defined keywords in any language through June 2020. Studies that compared the effect of cinnamon with placebo on insulin resistance (IR) indices, as the primary outcome, in women with polycystic ovary syndrome (PCOS) were considered eligible. Standard Mean difference (SMD) (with 95% confidence intervals) for endpoints were calculated using the random-effects model. Finally, five RCTs which met the criteria were included in the meta-analysis. After pooling data, cinnamon supplementation significantly reduced homeostatic model assessment for insulin resistance (HOMA-IR) scores in women with PCOS (SMD: -0.84, 95% CI: -1.52, -0.16, p = .010). Cinnamon supplementation likely improves certain IR markers in patients with PCOS. Practical applications There are controversies reports for cinnamon intake, which animal models have suggested that it decreases IR via promotion of insulin action, stimulating insulin signaling pathways, and enhancing insulin sensitivity. This study provides comprehensive information about the effect of cinnamon on insulin resistance (IR) indices in women with PCOS. In this regard, our results indicated that cinnamon supplementation significantly reduced homeostatic model assessment for insulin resistance (HOMA-IR) scores in women with PCOS. Therefore, consumption of cinnamon can be safe and this can be a useful recommendation for improving IR and promotion of healthy life which indeed are the potential or actual uses of this research.