Inositol for polycystic ovary syndrome PCOS guidelines: a systematic review and meta-analysis to inform the 2023 update of the international evidence-based

Insulin resistance is common in women with Polycystic Ovary Syndrome (PCOS). Inositol may have insulin sensitising effects; however, its efficacy in the management of PCOS remains indeterminate. To inform the 2023 International Evidence-based Guidelines in PCOS, this systematic review and meta-analysis evaluated the efficacy of inositol, alone or in combination with other therapies, in the management of PCOS. Medline, PsycInfo, EMBASE, All EBM, and CINAHL from inception until August 2022. Thirty trials (n=2230; 1093 intervention, 1137 control), with 19 pooled in meta-analyses were included. Data were extracted for hormonal, metabolic, lipids, psychological, anthropometric, reproductive outcomes and adverse effects by one reviewer, independently verified by a second. Thirteen comparisons were assessed, with three in meta-analyses. Evidence suggests benefits for myo-inositol or D-chiro-inositol (DCI) for some metabolic measures and potential benefits from DCI for ovulation but inositol may have no effect on other outcomes. Metformin may improve waist-hip ratio and hirsutism compared to inositol but there is likely no difference for reproductive outcomes, and the evidence is very uncertain for BMI. Myo-inositol likely causes fewer gastrointestinal adverse events compared with metformin; however, these are typically mild and self-limited. The evidence supporting the use of inositol in the management of PCOS is limited and inconclusive. Clinicians and their patients should consider the uncertainty of the evidence together with individual values and preferences when engaging in shared decision-making regarding the use of inositol for PCOS.