Metformin for PCOS (2026)
Quick answer: Metformin (typically titrated from 500 mg up to 1500-2000 mg/day) improves insulin sensitivity and can improve cycle regularity in PCOS. The 2023 International Evidence-based PCOS Guideline supports it for metabolic features — it is most useful in insulin-resistant phenotypes, not every PCOS presentation.
Metformin in PCOS care
Insulin resistance sits at the center of many PCOS presentations: elevated insulin drives the ovaries to produce more androgens and worsens the metabolic picture. Metformin improves insulin sensitivity, which is why it can improve cycle regularity and modestly help weight and metabolic markers in the phenotypes where insulin resistance is prominent.
The 2023 International Evidence-based PCOS Guideline supports metformin for management of metabolic features in adults with PCOS, particularly at higher BMI, and as an option alongside lifestyle change. It is not a universal PCOS drug — adrenal-pattern or lean phenotypes without insulin resistance gain less from it, which is why phenotype matters before starting.
Practical notes: gastrointestinal side effects (nausea, loose stools) are common early and are managed by slow titration or extended-release formulations; long-term use can lower vitamin B12, which is worth periodic checking; and metformin supports ovulation in some women, so contraception planning should be explicit if pregnancy is not the goal.