Metformin is most commonly prescribed oral insulin sensitising agents. In the past two decades, its properties as an insulin sensitising agent have been explored in relation to its applicability for women with Polycystic ovary syndrome (PCOS). PCOS is an endocrinopathy characterised by increased resistance to insulin.
However, more research is required to define whether metformin has a role in improving long term health outcomes for women with PCOS, including the prevention of diabetes, cardiovascular disease and endometrial cancer.

The current review in European Journal of Endocrinology evaluates the effectiveness of metformin and lifestyle modification compared with placebo in the management of PCOS and will inform the forthcoming, 2023 evidence-based PCOS guidelines.
The study suggests that Metformin is an efficacious supplement to lifestyle interventions in adults with PCOS, especially for those with a higher BMI, to improve weight loss, insulin resistance and lipids.
The researchers conducted a systematic review and meta-analysis of the literature. A search was performed in MEDLINE, EMBASE, PsycINFO, All EBM and CINAHL. The review was conducted according to PRISMA guidelines and included randomized controlled trials published in English through July 2022.
The key findings of the review are
• Moderate certainty of evidence showed a larger reduction of body mass index (BMI) (mean difference (MD) -0.53, 95%CI -0.95 to -0.12 kg/m2).

• Homeostatic model assessment for insulin resistance (MD -0.50, 95% CI -0.91 to -0.09) (critical outcomes) and fasting glucose (MD -0.13, 95% CI -0.19 to -0.07 mmol/l) with metformin compared to placebo with increased mild gastrointestinal adverse effects (OR 7.67, 95% CI 2.74 to 21.46).
• Low certainty of evidence showed a larger reduction of waist-hip ratio (MD -0.02, 95% CI -0.03 to -0.00), total cholesterol (MD -0.24, 95% CI -0.43 to -0.05 mmol/l), low-density lipoprotein (MD -0.16, 95% CI -0.30 to -0.01 mmol/l) and triglycerides (MD -0.11, 95% CI -0.20 to -0.02 mmol/l) with metformin than placebo.
Researchers concluded that “Metformin should be considered as an efficacious adjunct to lifestyle interventions in adults with PCOS, especially for those with a higher BMI, to improve weight loss, insulin resistance and lipids.”
Reference: Johanna Melin and others, The impact of metformin with or without lifestyle modification versus placebo on polycystic ovary syndrome: A systematic review and meta-analysis of randomized controlled trials, European Journal of Endocrinology, 2023;, lvad098, https://doi.org/10.1093/ejendo/lvad098.