PCOS / PMOS and insulin resistance

A new name

In 2026 polycystic ovary syndrome (PCOS) was renamed polyendocrine metabolic ovarian syndrome (PMOS). The "cysts" in the old name are normal egg follicles whose development has paused, and the name left out the parts of the condition outside the ovary: the hormones and the metabolism. The diagnostic criteria are unchanged. Both names will be used side by side for a while.

How common it is

Between one in ten and one in eight women of reproductive age.

Insulin resistance and androgens

Many women with PCOS / PMOS are insulin resistant, whatever their weight. To keep glucose normal the body makes more insulin, and high insulin levels stimulate the ovaries to make more androgens (male-type hormones) and reduce the protein that normally binds them. Raised androgens cause acne, unwanted hair and disrupted ovulation.

For women above a healthy weight, losing 5 to 10% of body weight can improve periods and symptoms. Insulin resistance doesn't make weight loss impossible, though many women find weight harder to manage, and that deserves to be taken seriously rather than put down to effort.

Getting the diagnosis right

In adults, two of: irregular or absent ovulation; raised androgens on examination or blood test; polycystic ovaries on ultrasound, or, since 2023, a raised AMH blood test in place of the scan. No scan or AMH test is needed if periods are irregular and androgens are raised. In the first eight years after periods start, ultrasound and AMH aren't used.

Conditions to rule out: thyroid disease, a raised prolactin, non-classic congenital adrenal hyperplasia (a 17-hydroxyprogesterone blood test), and, if symptoms are severe or appear quickly, cortisol excess or an androgen-producing tumour.

Long-term health

PCOS / PMOS raises the risk of type 2 diabetes, including diabetes in pregnancy, and of raised cholesterol and blood pressure, so the guideline advises regular glucose and cardiovascular checks. It is also linked to anxiety and low mood, which deserve attention in their own right.

What an appointment covers

Treatment follows your priorities: regular periods, skin and hair, weight, fertility or long-term health. Options include lifestyle change, medicines that improve insulin sensitivity, hormonal treatment for periods and skin, and medicines that block androgen effects. When I see you, I confirm the diagnosis, check for the conditions above, and set out a plan around what matters most to you.