Why is PCOS treated as a metabolic condition?

PCOS is a reproductive diagnosis with a metabolic engine. Insulin resistance is common in PCOS and it does two things at once: it pushes the ovarian theca cells to produce more androgen, and it suppresses sex hormone binding globulin made by the liver, so a larger fraction of the testosterone already present is free and active. That is why the same condition produces both irregular cycles and acne, hair growth and weight that is hard to shift.

How insulin raises testosterone

In PCOS, insulin acts as a co-gonadotrophin. Alongside luteinising hormone, it stimulates androgen output from the ovary. At the same time, insulin lowers hepatic production of sex hormone binding globulin, the carrier protein that keeps most circulating testosterone inactive. Lower carrier protein means higher free testosterone at the same total level. This is the mechanism behind the observation that lowering insulin, by whatever route, tends to lower androgen symptoms over months rather than days.

What the guideline says about diabetes risk

The 2023 International Evidence-based Guideline states that women with PCOS have an increased risk of impaired fasting glucose, impaired glucose tolerance and type 2 diabetes "regardless of age and BMI". It recommends the 75 g oral glucose tolerance test as the most accurate test of glycaemic status in PCOS, again regardless of BMI, and reassessment every one to three years depending on other risk factors. Fasting glucose and HbA1c alone miss a meaningful number of these cases.

What this changes about treatment

Framing PCOS as metabolic changes what gets measured and what gets treated. It means a lipid profile at diagnosis regardless of age and BMI, annual blood pressure, and screening for obstructive sleep apnoea, which the guideline notes is more common in PCOS independent of body weight. It also explains why metformin is positioned for metabolic features rather than for periods, and why exercise plus a diet the person can actually sustain sits at the base of every treatment plan.

If you have PCOS and have never had an oral glucose tolerance test, that is the single test to ask for. Bring the result back with your lipids and blood pressure, and set a recheck interval of one to three years rather than leaving it open.