Can insulin resistance cause PCOS?

Note on the name: in May 2026, polycystic ovary syndrome (PCOS) was formally renamed polyendocrine metabolic ovarian syndrome (PMOS), following a global consensus process. The old name was inaccurate — the condition affects multiple hormone and metabolic systems, not just the ovaries, and "polycystic" wrongly implies ovarian cysts. Nothing about the condition, its diagnosis or its treatment has changed. Both names will be used side by side for the next few years, and we use PCOS below since that is the term most people know.

Insulin resistance is central to PCOS in a majority of women, though the relationship is not quite one of simple cause. What happens: cells respond poorly to insulin, so the body produces more of it. High circulating insulin prompts the ovaries to produce more androgens and lowers the protein that binds testosterone in the blood, leaving more of it active. That combination disrupts the follicle development needed for ovulation. Importantly, insulin resistance in PCOS is not solely explained by weight. Lean women with PCOS can have it too, which is why testing should not be reserved for those who are overweight. What helps: reducing refined carbohydrates and sugar, regular exercise — resistance training and aerobic activity both improve insulin sensitivity independently of weight loss — and weight reduction where relevant. Medication such as metformin is used in some circumstances and needs prescribing and monitoring. Worth asking your doctor about: a fasting glucose and HbA1c, since PCOS carries a raised long-term risk of type 2 diabetes, and screening is often overlooked in younger women. This matters beyond fertility.