Insulin resistance in women: signs, the tests that check it, and what HbA1c means.
Insulin resistance means your cells respond less well to insulin, so your body makes more of it to keep blood sugar normal. It is common in women, closely tied to PCOS and to the perimenopausal years, and it is checked with a small set of blood tests: fasting glucose, HbA1c and a lipid profile, read together.
What insulin resistance is
After you eat, glucose enters your blood and your pancreas releases insulin, the hormone that tells muscle, liver and fat cells to take the glucose in. When cells become less responsive, the pancreas compensates by producing more insulin. For years that works: blood sugar stays normal and nothing shows on a standard glucose test. What has changed is that insulin levels are running high all the time.
High insulin has effects of its own. It encourages fat storage around the middle, drives appetite and cravings, raises triglycerides, lowers protective HDL cholesterol, and in women it nudges the ovaries to make more testosterone. Over time, if the pancreas cannot keep up, glucose starts to rise, first into the "pre-diabetes" range and eventually into type 2 diabetes. Insulin resistance is the long, quiet stage before that, and it is the stage where testing is most useful.
The 7 signs of insulin resistance
None of these proves insulin resistance on its own, and several are simply common. Two or three together, especially with a family history, are a reasonable prompt to test.
- Weight that settles around your middle and resists the changes that used to shift it, particularly a waist measurement that keeps creeping up.
- Energy crashes after meals, a mid-afternoon slump, or feeling shaky and irritable if a meal is late.
- Cravings for sweet or starchy food and feeling hungry again soon after eating.
- Skin changes: darker, velvety patches at the back of the neck, armpits or groin (acanthosis nigricans), and small skin tags in the same places.
- Irregular or absent periods, adult acne or excess facial and body hair, the features of PCOS, which is closely linked to insulin resistance in most women who have it.
- Raised blood pressure, high triglycerides or low HDL turning up on a routine check, often years before glucose changes.
- A family history of type 2 diabetes, or gestational diabetes in your own pregnancy, both of which raise your risk substantially.
Two of these are distinctly female. PCOS is the most common hormonal condition in women of reproductive age, and insulin resistance sits underneath it for the majority. And in perimenopause, falling oestrogen shifts fat storage from hips to abdomen and reduces insulin sensitivity, which is why so many women notice their shape change in their late forties despite doing nothing differently.
The tests: fasting glucose, HbA1c and lipids
There is no single "insulin resistance test" in routine Australian practice. Doctors build the picture from three measurements, each adding a piece.
- Fasting glucose: your blood sugar after 8 to 12 hours without food. In Australia, below 5.5 mmol/L makes diabetes unlikely; 5.5 to 6.9 mmol/L is an uncertain band where a glucose tolerance test is usually arranged (6.1 to 6.9 mmol/L is formally called impaired fasting glucose); 7.0 mmol/L or above, confirmed on a second occasion, is in the diabetes range. It is a late marker: it stays normal until the pancreas begins to fall behind.
- HbA1c: the percentage of your haemoglobin that has glucose attached, reflecting average blood sugar over roughly the previous three months. No fasting needed. It smooths out day-to-day variation and is one of the tests used to diagnose diabetes in Australia, alongside fasting glucose and the oral glucose tolerance test.
- Lipid profile: total, LDL and HDL cholesterol plus triglycerides. Insulin resistance has a recognisable fingerprint here: high triglycerides with low HDL. It also feeds into your longer-term cardiovascular risk, which is the reason insulin resistance matters.
Read together, a fasting glucose creeping upwards, a borderline HbA1c, high triglycerides and low HDL tell a clear story. Any one of them alone is much less informative.
Fasting insulin, and the HOMA-IR index calculated from it, come up often online. The assay is not standardised between laboratories, there is no agreed cut-off, and the 2023 International PCOS Guideline recommends against using either to decide whether an individual is insulin resistant. They remain useful in research and occasionally in specialist assessment, and they are not part of the KnowLuna panels, which use fasting glucose and HbA1c.
HbA1c ranges in Australia
| HbA1c | Category | What it usually means |
|---|---|---|
| Below 6.0% (below 42 mmol/mol) | Normal range | Average blood sugar over three months is in the normal band. It does not rule out insulin resistance, which shows up in insulin and lipids first. |
| 6.0 to 6.4% (42 to 47 mmol/mol) | Higher risk ("pre-diabetes" range) | Blood sugar is running above normal. Doctors usually repeat it, check fasting glucose, and talk about risk factors. |
| 6.5% and above (48 mmol/mol and above) | Diabetes range | In the diabetes range; a diagnosis needs a repeat or a second test unless you have clear symptoms. Your doctor arranges follow-up. |
Ranges vary by laboratory; your report shows the range your lab uses. Typical ranges on this page are drawn from Pathology Tests Explained (RCPA) and the sources listed below.
Two caveats matter for women. HbA1c depends on red blood cells living a normal lifespan, so iron deficiency, anaemia, recent blood loss and pregnancy can all distort it, sometimes making it read higher or lower than your true average. If your ferritin is low or you are pregnant, your doctor may lean more on glucose. And HbA1c is a poor early detector of insulin resistance: by the time it moves, the process has usually been under way for years.
Insulin resistance, PCOS and perimenopause
In PCOS, high insulin acts on the ovaries and reduces SHBG, the protein that binds testosterone, so more free testosterone circulates. That is the link between a metabolic problem and acne, hair changes and irregular ovulation. It is why a proper PCOS assessment includes fasting glucose, HbA1c and lipids alongside the hormones, and why women with PCOS are advised to have their metabolic markers checked regularly over the years, not once.
Perimenopause brings a second wave. As oestrogen falls, insulin sensitivity drops, abdominal fat increases and cholesterol patterns often worsen, all within a few years. Women who sailed through their thirties can find their fasting glucose and lipids drifting in their late forties. A baseline in perimenopause, and again after menopause, gives you and your doctor something to compare against rather than guessing.
What this article will not do is tell you how to fix it. Whether and how insulin resistance is managed is a conversation between you and your doctor, informed by the numbers, your history and your goals.
Your KnowLuna weight and metabolic check
The KnowLuna weight and metabolic check measures fasting glucose, HbA1c, a lipid profile and liver function, and adds TSH, testosterone, SHBG, cortisol and uric acid so the thyroid and hormone contributors are checked in the same sample. Fast for 8 to 12 hours (water is fine) and collect in the morning at an accredited centre, or choose a home kit or a nurse visit where the test allows it. Your report shows each marker against the laboratory range with a plain-English note, and any result that needs attention is followed up by a doctor.
Common questions
How do you test for insulin resistance in Australia?
There is no single routine test. Doctors combine fasting glucose, HbA1c and a lipid profile with your symptoms and history. A fasting glucose in the uncertain band, plus high triglycerides and low HDL, is the typical early pattern. Fasting insulin and HOMA-IR are not recommended for assessing an individual, because the insulin assay is not standardised between laboratories. An oral glucose tolerance test is the most accurate check of how your body handles glucose, and it is a routine two-hour test at a collection centre rather than a specialist one.
What is a normal HbA1c level in Australia?
Below 6.0% (42 mmol/mol) is normal, 6.0 to 6.4% is the higher-risk or "pre-diabetes" range, and 6.5% (48 mmol/mol) or above is in the diabetes range when confirmed on a repeat. Age does not change the diagnostic thresholds, although your doctor may interpret a borderline result differently depending on your overall risk. Ranges vary slightly by laboratory.
Do I need to fast for an HbA1c test?
No. HbA1c reflects average glucose over about three months, so a recent meal does not change it. Fasting glucose and triglycerides do need 8 to 12 hours without food, which is why panels that include them ask for a morning collection. Water is fine, and you should take usual medicines unless your doctor says otherwise.
What is a normal fasting insulin level?
Laboratory ranges for fasting insulin are wide and there is no single agreed cut-off for insulin resistance, which is why guidelines recommend against using it to assess an individual and why it is not in the KnowLuna panels. If your doctor has requested one, they interpret it alongside glucose, HbA1c, lipids and your symptoms rather than against one number.
How do you know you are insulin resistant?
Usually from the combination of signs (central weight, cravings, energy crashes, skin changes, PCOS features, abnormal lipids or blood pressure, family history) and a pattern on blood tests: a fasting glucose drifting up, high triglycerides, low HDL, and sometimes an HbA1c in the higher-risk range. A doctor puts those together; no symptom or single result settles it alone.
Does PCOS always mean insulin resistance?
Not always, but it is present in the majority of women with PCOS, including many at a healthy weight. Australian PCOS guidance recommends checking metabolic markers such as glucose, HbA1c and lipids at diagnosis and periodically afterwards. If you have PCOS and have never had glucose, HbA1c or lipids measured, it is a reasonable thing to ask about.
Sources and further reading
- Pathology Tests Explained (RCPA): HbA1c
- Pathology Tests Explained (RCPA): glucose
- Pathology Tests Explained (RCPA): insulin
- Monash University: International Evidence-based Guideline for the Assessment and Management of PCOS 2023
- RACGP: Management of type 2 diabetes, a handbook for general practice
- Healthdirect: pre-diabetes
- Better Health Channel: pre-diabetes
General information only, not medical advice. If your symptoms are severe or sudden, see a doctor promptly. This page does not replace a consultation with a doctor who knows your history; read our medical disclaimer.
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