What Is Insulin Resistance? Signs in Women and the PMOS Link

Insulin resistance comes up constantly in conversations about PMOS (formerly PCOS), prediabetes and weight, but it is rarely explained well. In short, your body stops responding to insulin as well as it should, so it makes more of it to keep blood glucose in range. This guide explains what insulin resistance is, the signs, how it is (and isn’t) tested, why it is so closely linked with PMOS, and what research says helps.

What is insulin resistance?

Insulin is the hormone that moves glucose from your blood into your cells. Diabetes Australia describes insulin resistance as the body no longer responding to insulin in the way it should: insulin becomes less effective, so more is needed. Diabetes WA explains that the pancreas works harder to make more insulin, and over time it can tire. That is why insulin resistance often comes before prediabetes and type 2 diabetes. Diabetes Australia estimates two million Australians have prediabetes.

Signs to look for

Most people with insulin resistance feel nothing. Healthdirect notes there are normally no symptoms of prediabetes. When there are signs, they are subtle: Diabetes WA mentions dark patches of skin, especially around the neck and armpits. Diabetes Australia lists factors linked with insulin resistance including carrying weight around the waist, inactivity, family history, ethnicity, age and PMOS.

How it is tested

There is no simple, accurate routine blood test for insulin resistance. The 2023 International PCOS Guideline says routinely available measures of insulin resistance are inaccurate, clinical measurement is not currently recommended, and insulin blood tests should not be used in routine care. What doctors do test is blood glucose. Healthdirect describes a fasting or random blood glucose and an HbA1c test, followed by an oral glucose tolerance test if results are raised. For women with PMOS, the guideline names the oral glucose tolerance test as the most accurate test of glucose status.

The PMOS link

Insulin resistance is recognised as a key feature of PMOS. Jean Hailes reports it affects between 44% and 85% of women with the condition. In a small Australian study using the gold-standard clamp test, insulin resistance was found in 75% of lean women with PCOS, 62% of overweight women without it and 95% of overweight women with it. A meta-analysis of clamp studies found insulin sensitivity was about 27% lower in PCOS regardless of body size, with higher weight making it worse. So insulin resistance in PMOS is not simply about weight. Higher insulin can also drive higher androgen levels, which links it to symptoms like irregular cycles, acne and excess hair.

What helps

The best-known evidence comes from the US Diabetes Prevention Program, where a lifestyle program of eating changes and regular activity reduced new cases of type 2 diabetes by 58% in people at high risk, more than metformin did (31%). Physical activity can improve insulin sensitivity even without weight loss, and a meta-analysis in PCOS found vigorous exercise had the greatest effect on insulin resistance, although another review of exercise trials in PCOS found no change. A 2020 meta-analysis of 57 trials found the Mediterranean diet improved many markers of metabolic health, including insulin resistance.

In practice, that usually means regular meals with fibre-rich carbohydrates like wholegrains, legumes, vegetables and fruit, enough protein, healthy fats like olive oil and nuts, and moving your body in ways you enjoy. Extreme low-carbohydrate or very restrictive diets are not needed, and the PCOS guideline advises against unduly restrictive diets. If weight has been a source of distress, a weight-neutral approach can still improve insulin sensitivity.