PCOS and Insulin Resistance: Signs and the Tests to Ask For

The short answer: Insulin resistance means your cells have stopped responding properly to insulin, so your body makes extra. That extra insulin pushes your ovaries to make more male-type hormones, which is what disturbs ovulation and turns periods irregular in PCOS. It affects most women with PCOS, slim women included. There is no single tidy "insulin resistance test", so what your doctor actually checks is your blood sugar, usually with a glucose tolerance test, along with signs she can see on your skin and around your waist.

What is insulin resistance?

Insulin is the hormone that moves sugar out of your blood and into your cells, where it is used for energy. In insulin resistance, the cells stop listening to that instruction properly. Your blood sugar stays up longer, so your body compensates by making more and more insulin.

For a while this works. Your sugar readings can look completely normal while your insulin level is quietly high. That is why many women are told "your sugar is fine" and still feel that something is off.

The problem is what all that extra insulin does elsewhere. It lowers a protein called SHBG that normally keeps testosterone bound and inactive, so more free testosterone circulates. It also pushes the ovary directly to make more androgens, the male-type hormones. Those androgens disturb ovulation, which is why periods turn irregular, and they drive the acne and the extra facial hair.

Weight around the waist worsens insulin resistance further, which is how the loop closes and keeps turning. Breaking it anywhere slows the whole cycle down, and that is what treatment is aiming at.

How common is insulin resistance in PCOS?

It is the usual state, not the exception. Estimates put insulin resistance in roughly 35% to 80% of women with PCOS, and the range is that wide because there is no single agreed way to measure it. UK guidance puts it at around 65% to 80%, and states plainly that it happens independent of obesity.

Read that last number again if you are slim. Insulin resistance in PCOS happens regardless of weight, and being thin is not a reason to skip testing. Research also suggests women of South Asian origin develop PCOS younger and with stronger symptoms than the women in most Western studies, which makes this directly relevant to us here.

For context on PCOS itself, an Indian review that pooled 11 studies found about 11 in 100 women affected, though estimates swing widely with the region and the definition used. Worldwide, the World Health Organization estimates 10% to 13% of women of reproductive age, and says up to 70% of them are never diagnosed.

What are the signs of insulin resistance?

Some you can see, some you only feel. None of them proves insulin resistance on its own, but together they tell your doctor where to look.

The most useful visible sign is acanthosis nigricans: dark, velvety, slightly thickened patches of skin, usually on the back of the neck, in the armpits, or in the groin. Women often tell me it is dirt that will not scrub off. It is not dirt, and no amount of scrubbing or bleaching cream will clear it. It is a skin change that goes with high insulin, and it is worth showing your doctor.

Other things to notice and mention:

• Weight settling around the middle rather than the hips
• Skin tags, small soft flaps of skin on the neck or underarms
• Strong cravings for rice, sweets or bakery food, and heavy sleepiness after a big meal
• Energy crashes in the afternoon
• Periods that are getting further apart
• Acne along the jaw, or increasing facial hair

One honest caution about those dark patches. Almost always they point to insulin resistance. Occasionally they have another cause, including some medicines, and rarely they can be a sign of a more serious illness, particularly when they appear suddenly and spread fast in someone who is not overweight. That is not a reason to panic. It is the reason to have a doctor look at them instead of diagnosing yourself online.

Measure your waist

This is the one check you can do at home tonight, and it is more useful than any supplement. Take a measuring tape around your waist at the level of your navel, standing relaxed, breathing out normally.

For Indian women, 80 centimetres and above counts as abdominal obesity. That is deliberately lower than the number used for European women, because we develop the metabolic risk at a smaller size. A simpler version of the same idea, if you have no tape: your waist should measure less than half your height.

The same logic applies to weight charts. Indian consensus guidelines set the cut-offs lower than the international ones, with a BMI above 23 already counting as raised where the standard chart only starts at 25. If you want to see where you stand, my free BMI calculator will tell you in a moment.

Two symptoms are different in kind and mean you should be seen sooner rather than later: heavy thirst with passing urine often, which can point to diabetes, and the virilisation signs described in the red-flag box below.

Which tests should I ask for?

Here is the honest part that most articles skip. There is no single, simple, agreed test for insulin resistance in ordinary clinical practice. What gets checked is how your body handles sugar, plus the tests that rule out other conditions.

What we test instead is the consequence: how your body handles sugar. The test to ask for is the oral glucose tolerance test. You come fasting, a blood sample is taken, you drink a measured sweet glucose solution, and a second sample is taken two hours later. The 2023 international guideline calls it the most accurate way to check blood sugar in PCOS, and it says so regardless of your weight.

What do the numbers mean?

Here are the screening thresholds used by the American Diabetes Association, the ones most commonly applied. Anything below the middle column is normal.

Test	In-between stage (prediabetes)	Diabetes
Fasting blood sugar	100 to 125 mg/dL	126 mg/dL or above
2-hour glucose tolerance test	140 to 199 mg/dL	200 mg/dL or above
HbA1c	5.7% to 6.4%	6.5% or above

One result is not a diagnosis, unless you are pregnant. Outside pregnancy, and unless your sugar is very high and you already have clear symptoms, diabetes is confirmed on two abnormal results, either two tests done together or a repeat done promptly. So do not diagnose yourself from a single report; bring it in and we will confirm it properly.

Pregnancy is the exception, and it matters. Diabetes in pregnancy is diagnosed on a single abnormal sugar test, so a pregnant woman must never wait for a second one to take a high reading seriously. If you are pregnant, the thresholds above are not yours; follow the testing your antenatal care sets out, and tell your doctor the same day if a reading comes back high.

A reading in that middle column is not a disaster. It is the stage where changes work best, and it is exactly the reading I would rather find now than in ten years.

If a glucose tolerance test genuinely cannot be arranged, a fasting sugar or an HbA1c is better than nothing, but the guideline is clear that both are noticeably less accurate in PCOS. And there is a reason I am extra careful with HbA1c here. HbA1c is measured on your red blood cells, so anything that changes those cells changes the reading. The American Diabetes Association says HbA1c may not be a suitable diagnostic test in people with anaemia, and that where red-cell turnover is altered the plasma glucose tests should be used instead. Low haemoglobin is common among Indian women. If you are anaemic, trust the sugar tests.

Your doctor will usually also run the tests that exclude other causes, because thyroid disease and a raised prolactin level produce very similar symptoms: a thyroid test (TSH), prolactin, and a hormone called 17-hydroxyprogesterone. Testosterone may be measured too, though normal ranges differ between laboratories, so the result is read alongside what can be seen, never on its own.

A blood sugar check belongs at diagnosis for everyone with PCOS, then repeats every one to three years depending on your other risk factors, and yearly if a first test came back borderline. Blood pressure once a year, and again whenever you are planning a pregnancy. A cholesterol panel at diagnosis.

What about fasting insulin and HOMA-IR?

You will see these pushed constantly online, often by websites selling test panels, so let me save you some money. The 2023 international guideline states that the insulin tests available in ordinary labs are of limited clinical relevance and are not recommended in routine care.

HOMA-IR is not really a test at all. It is a sum: someone takes your fasting sugar and your fasting insulin, puts them into a formula, and the answer is an estimate of insulin resistance rather than a measurement of it. And there is no agreed line to compare your answer against. Different studies use 2.0, 2.5, 3.16. The same result can be called abnormal by one lab's range and normal by another's. The International Diabetes Federation says the same thing from a different direction: insulin resistance is difficult to measure in day-to-day practice, and it lists these among tests for research studies, not for the clinic.

I want to be careful not to overshoot here. This does not mean insulin testing is worthless, and it certainly does not mean you need no testing. If you have already had one done, bring it and I will read it as one piece of the picture. It means the test you read about online is not the one to ask for, and the glucose tolerance test is.

How is PCOS itself confirmed?

PCOS is diagnosed on the Rotterdam criteria: any two of the following three, once other causes have been ruled out.

Feature	What it means in practice
Irregular or absent ovulation	Cycles shorter than 21 days or longer than 35 days
Signs of high androgens	Acne or extra facial and body hair, or a blood test showing it
Polycystic-looking ovaries	Seen on ultrasound, or an AMH blood test in adults instead

Three practical points come out of the 2023 international guideline, which is still the current one in 2026.

• You may not need a scan at all. If you already have both irregular cycles and clear signs of high androgens, that is two of the three, and neither an ultrasound nor an AMH test is necessary to make the diagnosis. This surprises many women who have been told a scan is compulsory.
• In adults, an AMH blood test can stand in for the ultrasound. It cannot be used on its own to diagnose PCOS.
• For teenagers the rule is different, and it matters. Ultrasound should not be used to diagnose PCOS in adolescence, and neither should AMH, because normal young ovaries often look polycystic. A teenager needs both irregular cycles and signs of high androgens before we call it PCOS.

Not sure whether any of this applies to you? My free PCOS self-assessment takes two minutes and tells you whether testing is worth doing. If your periods are irregular, it is also worth knowing that PCOS is only one of several possible causes; my complete guide to irregular periods walks through the others, and thyroid problems are covered in my thyroid guide for Indian women.

Why does this matter in the long run?

Because insulin resistance is the part of PCOS that reaches beyond your periods. Women with PCOS have a higher risk of impaired glucose readings and type 2 diabetes, and that holds regardless of age and weight. Diabetes in PCOS also tends to appear earlier. This is exactly why I screen slim women too, and why I would rather find a borderline reading now than a diagnosis in ten years.

Two other things worth knowing while we are being honest about risk. Long stretches without periods let the womb lining keep building up, and over years that raises the risk of the lining becoming abnormal. Research puts the risk of cancer of the womb lining at roughly three times higher, but I want to be careful with that number: it is a relative risk, the underlying condition is uncommon, the evidence behind it is graded weak, and routine screening is not recommended. It is a reason to treat missing periods, not a reason to be frightened.

And the reassurance women most often need: PCOS does not increase your risk of breast cancer or ovarian cancer. No extra screening is needed beyond what any woman should have.

Your questions, answered

Can I have insulin resistance with a normal sugar report?

Yes, and this is common. Early on your body compensates by making extra insulin, which keeps your blood sugar in the normal range. A normal fasting sugar does not rule out insulin resistance, which is why the glucose tolerance test, which watches how you handle a sugar load, tells us more.

Is insulin resistance the same as diabetes?

No. Insulin resistance is your cells responding poorly to insulin. Diabetes is diagnosed when blood sugar crosses defined levels. Insulin resistance can exist for years with normal sugar, and it raises the risk of diabetes later, which is why we check regularly rather than once.

I am slim. Can I still have insulin resistance?

Yes. UK guidance states that insulin resistance in PCOS occurs independent of obesity, so a normal weight does not rule it out. Lean PCOS is real, and that same guidance says South Asian women should have the glucose tolerance test whatever their weight.

Will the dark patches on my neck go away?

They often improve when the cause underneath is treated, though it is gradual and it is not the first thing to shift. Scrubbing, bleaching creams and salon treatments do not address the cause. Treat what is driving it and the skin usually follows.

Does PCOS always mean insulin resistance?

Not always, but usually. Estimates run from about 35% up to 80% of women with PCOS, and it is present in most. Your own picture is worked out from your sugar handling and your signs, not assumed.

My report says polycystic ovaries but my periods are regular. Do I have PCOS?

Probably not. Polycystic-looking ovaries alone are one feature, and diagnosis needs two of the three. Many women with normal cycles have ovaries that look like that on a scan. If your periods are regular and you have no signs of high androgens, a scan finding on its own does not make it PCOS.

Once you know insulin resistance is part of your picture, the next question is what to do about it. That is the whole subject of my companion guide on how to treat and manage insulin resistance, which covers the eating pattern, exercise, sleep, and where metformin and the newer medicines honestly fit. For food specifically, start with my PCOS diet guide for Indian foods.

Sources for this article (11)

1. Teede et al., International Evidence-based Guideline for the Assessment and Management of PCOS, JCEM, 2023 (accessed July 2026)
2. RCOG Green-top Guideline No. 33, Long-term Consequences of Polycystic Ovary Syndrome, 2014 (accessed July 2026)
3. WHO fact sheet: Polycystic ovary syndrome, 2026 (accessed July 2026)
4. Bharali et al., Prevalence of PCOS in India: systematic review and meta-analysis, Cureus, 2022 (accessed July 2026)
5. Pena et al., International evidence-based recommendations for PCOS in adolescents, BMC Medicine, 2025 (accessed July 2026)
6. Nordic perspective on the 2023 international PCOS guideline, 2023 (accessed July 2026)
7. Review: insulin resistance in PCOS, Frontiers in Endocrinology, 2025 (accessed July 2026)
8. American Diabetes Association, Diagnosis and Classification of Diabetes: Standards of Care in Diabetes, 2026 (accessed July 2026)
9. Acanthosis Nigricans, StatPearls, NCBI Bookshelf, National Institutes of Health (accessed July 2026)
10. International Diabetes Federation: consensus worldwide definition of the metabolic syndrome (accessed July 2026)
11. Misra et al., Revised definition of obesity in Asian Indians living in India, Diabetes and Metabolic Syndrome, 2025 (accessed July 2026)

This article is for your information and learning. It is not a substitute for a consultation. For advice about your own health, talk to me or your own doctor.