If you have read anything about PCOS, you have met the phrase "insulin resistance". It is used so often that it can sound like a diagnosis in itself, or a verdict. It is neither. It is a description of how the body is handling one hormone, it is very common in PCOS, and it is one of the few parts of the condition that everyday habits can reach. This page is a starting point, not a substitute for the tests and conversation a doctor can offer.
What insulin resistance is
Insulin is a hormone made by the pancreas. Its job is to move glucose — sugar — out of the blood and into cells, where it is used for energy. Insulin resistance, as the NIDDK describes it, is a condition in which the body does not respond to insulin the way it should: cells in the muscles, fat and liver stop responding well, so glucose has a harder time getting in.
The pancreas compensates by making more insulin. For a while that works, but the body is running on higher insulin to do it. Over time the pancreas may not keep up, and blood glucose drifts upward. When it is higher than normal but not yet high enough to be diabetes, that is prediabetes; if it keeps going up, it becomes type 2 diabetes. The NIDDK also lists weight gain, higher blood pressure, unhealthy cholesterol and triglyceride levels, and fatty liver disease among the problems that travel with insulin resistance.
None of that is a fixed state. The NIDDK's own heading is "how can I prevent or reverse insulin resistance".
Why it is common in PCOS
The 2023 international guideline calls insulin resistance a pathophysiological factor in PCOS — part of the mechanism, not a coincidence. The NIDDK lists PCOS among the conditions that make insulin resistance and prediabetes more likely, alongside a family history of diabetes and being physically inactive. The NHS puts the cause of PCOS as unknown, but says it may be to do with hormones such as insulin and testosterone not working properly.
The consequence is a raised risk that does not depend on body size. The guideline is explicit that women with PCOS have an increased risk of impaired fasting glucose, impaired glucose tolerance and type 2 diabetes regardless of age and BMI. That is why it recommends checking glycaemic status at diagnosis and then every one to three years, and why the NHS lists type 2 diabetes, high blood pressure and cardiovascular disease among the complications to watch for.
How insulin connects to the symptoms you can see — the link from higher insulin to higher androgens to irregular cycles, hair growth and acne — is laid out in the PCOS diet guide. The short version is that insulin is the lever, which is why food matters more with PCOS than it does for most people.
How it shows up (cravings, energy dips, skin)
Here it is worth being honest about what the sources do and do not say. The NIDDK states that people with insulin resistance and prediabetes usually have no symptoms. The things people commonly describe — being hungry again soon after a carbohydrate-heavy meal, a slump in the middle of the afternoon, a pull towards sweet food when tired — are real experiences and worth paying attention to, but neither the NIDDK nor the guideline lists them as signs of insulin resistance, and none of them is a diagnosis.
What the NHS does list among the symptoms of PCOS is more concrete: thick, dark patches of skin on the neck or armpits (acanthosis nigricans), oily skin and acne, weight gain or difficulty losing weight, and feeling very tired. If you recognise the skin patches in particular, mention them to a GP; they are one of the visible clues that insulin is involved.
How it is tested
Not, usually, with an insulin test. The guideline says that clinically available insulin assays are of limited clinical relevance and are not recommended in routine care, and the NIDDK says the test for insulin resistance is primarily used in research studies. If a clinic offers to measure your insulin, the number it returns is less useful than it sounds.
What is tested is glycaemic status: how the body handles glucose. For PCOS the guideline recommends the 75-gram oral glucose tolerance test as the most accurate option, regardless of BMI. If that cannot be done, fasting plasma glucose or HbA1c could be used instead, noting significantly reduced accuracy. The NIDDK describes the same three tests, with HbA1c reflecting average blood glucose over the previous three months. The guideline also recommends a lipid profile at diagnosis, and an oral glucose tolerance test for anyone with PCOS who is planning a pregnancy. If you have not had your glucose checked since diagnosis, or it has been more than three years, that is a reasonable thing to ask for.
What moves it: food, movement, sleep
The NIDDK's list is short: healthy foods and drinks, being physically active, managing weight, and getting enough sleep. The guideline says the same in more words, recommending lifestyle intervention for all women with PCOS to improve metabolic health.
Food. On what to eat, the guideline finds no evidence that any one diet composition beats another, and warns against unduly restrictive diets. The pattern that works is ordinary healthy eating — vegetables, slower carbohydrates, protein at each meal, unsaturated fats — kept up over time. The carbohydrate side of that, and why pairing carbohydrate with protein and fibre matters, is covered in low-GI foods for PCOS; the meal most people get wrong is in PCOS breakfast ideas.
Movement. The guideline's targets match general population guidance: 150 to 300 minutes of moderate activity a week, or 75 to 150 minutes of vigorous activity, plus muscle-strengthening activity on two days. It is equally clear that some activity is better than none, and that replacing sitting time with movement of any intensity — including light — brings benefits. Walking counts.
Sleep. The NIDDK includes enough sleep in its list without elaborating. The guideline adds something specific to PCOS: obstructive sleep apnoea is significantly more common in women with PCOS than without, independent of BMI. If you snore and wake unrefreshed, or are sleepy or exhausted during the day, ask to be screened. It is treatable, and untreated it undermines everything else on this page.
Weight. The NIDDK cites the Diabetes Prevention Program, in which people at high risk who lost 5% to 7% of their starting weight reduced their chance of developing diabetes. The guideline frames weight carefully — it names weight stigma as a real harm and puts the priority on habits and preventing further gain rather than on a number.
In the app: the Glucose Predictor gives an estimate of how a meal may move blood sugar — its glycaemic load, worked out from the carbohydrate and glycaemic index you enter. It is an estimate, not a measurement, and it does not replace the tests above.
When medication enters
Lifestyle is the first step, not the only one. The guideline says metformin should be considered in adults with PCOS and a BMI of 25 or above for metabolic outcomes including insulin resistance, glucose and lipids, and may be considered below that BMI with more limited evidence. It also asks clinicians to tell women that metformin and an active lifestyle intervention have similar efficacy — the medicine is not a shortcut past the habits, and the habits are not a reason to refuse the medicine. The NHS lists metformin as a treatment for tiredness and weight problems in PCOS; side effects are mostly mild stomach upset that settles.
Inositol, the supplement most often sold for insulin resistance, gets a more cautious line: the guideline says it could be considered, with limited harm and some potential to improve metabolic measures, but limited clinical benefit for ovulation, hair growth or weight, and metformin is preferred over it for hair growth and central weight. Whatever you take, tell your doctor.
The decision about medication belongs in a consultation, with your test results in front of you. What this page can tell you is that insulin resistance in PCOS is common, expected, and responsive to the things you do every day.
Sources
- NIDDK — Insulin resistance and prediabetes
- Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of PCOS (Human Reproduction, full text at PMC)
- NHS — Polyendocrine metabolic ovarian syndrome (PMOS), previously called PCOS
This article is for education. It is not medical advice, diagnosis or treatment — talk to a clinician about your own care.
More in this series
- PCOS diet: what to eat, and why it works — What the evidence says about eating with PCOS: insulin, the pattern that helps, the foods worth limiting, and why no rigid plan is required.
- Anti-inflammatory eating for PCOS: what is real — Where "anti-inflammatory" and PCOS actually meet, which foods the evidence supports, which only marketing does, and how it overlaps with insulin advice.
- Foods to limit with PCOS, and why banning them backfires — The foods worth eating less often with PCOS, the evidence for each, and why "limit" beats "never" for a diet you can keep.
- Low-GI foods for PCOS: a practical list — What the glycaemic index does and does not tell you, which carbohydrates rank low, how protein and fat change the picture, and where GI stops helping.
- PCOS breakfast ideas that hold you until lunch — Why breakfast is where PCOS eating plans break, the protein-fibre-fat template that fixes it, ten breakfasts that use it, and what to do about coffee.
- A 7-day PCOS meal plan you can actually keep — Seven days of ordinary meals built on the pattern the evidence supports, with a shopping list and swaps, and no food group cut out.