PCOS: Why Insulin Sits at the Centre
Quick answer
PCOS can involve insulin resistance, irregular ovulation, and androgen symptoms, but mechanisms and symptoms vary. A clinician can assess metabolic and reproductive health and discuss options; do not use insulin-lowering medicines or supplements without advice, particularly when pregnant or trying to conceive.
PCOS affects more than the ovaries. We use Polyendocrine Metabolic Ovarian Syndrome (PMOS), the clinic’s preferred name, because it reflects the wider hormonal and metabolic picture. Insulin resistance is present in a large proportion of women with the condition, including many who are not overweight.
The mechanism
Higher circulating insulin stimulates ovarian androgen production and lowers sex hormone binding globulin, which raises free testosterone. That combination produces irregular or absent ovulation, acne, unwanted hair growth and hair thinning. It also makes weight gain easier and weight loss harder, which is experienced as personal failure and is in fact endocrinology.
Why diagnosis needs care
Diagnosis uses irregular ovulation, clinical or biochemical androgen excess and ultrasound appearance, with other causes excluded — thyroid disease, raised prolactin, and rarer adrenal causes. Ultrasound alone does not make the diagnosis, and normal ovaries do not exclude it.
What treatment addresses
- Insulin resistance: nutrition that steadies glucose, resistance training, and where appropriate metformin or, when licensed criteria are met, weight-management medication
- Cycle regularity and endometrial protection, which matters for long-term risk
- Androgen symptoms, which have their own treatments
- Long-term risk reduction for type 2 diabetes, fatty liver and cardiovascular disease
- Fertility, sequenced carefully — weight-management medicines must be stopped before conception
What we monitor
HbA1c or an oral glucose tolerance test, lipids, liver function, vitamin D and B12, thyroid function and androgen profile, reviewed over time rather than once.
The realistic picture
Modest weight reduction restores ovulation for a meaningful proportion of women, and even where cycles remain irregular, treating insulin resistance reduces long-term metabolic risk. PCOS is lifelong, but it is manageable, and the direction of travel changes markedly once insulin is addressed rather than ignored.
Reviewed by
Dr Chinnadorai Rajeswaran
Specialist Endocrinologist · MBBS MRCP FRCP
Last Reviewed: November 2026
Read about PCOS and related care.
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Weight and Fertility: Preparing the Body for Conception
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