What is insulin resistance?
Insulin is a hormone made by the pancreas. It helps move sugar (glucose) from your blood into your cells, where it is used for energy. In insulin resistance, muscle, fat and liver cells respond less well, so the pancreas works harder and makes more insulin.
For a while, this extra insulin keeps blood sugar in the normal range. Over time, the pancreas may not keep up, and blood sugar starts to rise, first into the prediabetes range and, for some people, into type 2 diabetes.
Does insulin resistance cause symptoms?
Usually not. The US National Institute of Diabetes and Digestive and Kidney Diseases notes that people with insulin resistance and prediabetes usually have no symptoms.
Some people notice clues that are associated with insulin resistance, although none of them proves it:
- darker, velvety skin in body folds such as the neck or armpits (called acanthosis nigricans);
- a larger waist or weight gained mainly around the abdomen;
- irregular periods or features of PMOS (polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome, or PCOS);
- raised triglycerides, low HDL cholesterol, or high blood pressure found on routine checks.
What raises the risk?
Common risk factors include:
- carrying excess weight, especially around the middle;
- low physical activity;
- age 35 and older;
- a family history of type 2 diabetes;
- diabetes during a previous pregnancy;
- PMOS (previously PCOS);
- smoking;
- some long-term medicines;
- certain ethnic backgrounds, with higher risk seen in people of South Asian and African descent, among others.
Short sleep is also linked to a higher risk of diabetes and weight gain.
How do doctors check for insulin resistance?
There is no standard routine test. Direct measures of insulin resistance are mainly used in research, and calculations based on fasting insulin are not standardised enough for routine diagnosis in most guidelines.
Instead, doctors usually look at a combination of clues:
| Clue | What it tells you |
|---|---|
| Waist circumference | Abdominal fat linked to insulin resistance |
| HbA1c or fasting blood sugar | Whether blood sugar has started to rise |
| Triglycerides and HDL cholesterol | A typical pattern (high triglycerides, low HDL) |
| Blood pressure | Often raised alongside insulin resistance |
| Liver tests or imaging | Fatty liver often goes with insulin resistance |
Taken together, these tell you far more than any single number.
What helps?
The good news: insulin sensitivity often improves with changes you can make.
- Move regularly. Both aerobic activity and muscle-strengthening help your muscles take up glucose. The World Health Organization recommends 150 to 300 minutes of moderate activity a week, plus regular strength training.
- Lose some weight if you carry excess weight. The Diabetes Prevention Program found that losing about 5% to 7% of starting body weight reduced the risk of developing type 2 diabetes.
- Eat mostly whole foods. Fewer sugary drinks and refined carbohydrates; more fibre, vegetables, legumes and protein.
- Prioritise sleep. Aim for seven or more hours a night.
- Stop smoking.
Some people also benefit from medicines. That decision depends on your overall picture and should be made with your doctor.
When to see a doctor
Speak to your doctor if you:
- notice darkening of the skin in body folds;
- have a waist of 94 cm or more (men) or 80 cm or more (women);
- have a family history of type 2 diabetes;
- have PMOS (PCOS) or had diabetes in pregnancy;
- have been told your sugar, triglycerides or blood pressure are "borderline".
Frequently asked questions
Is insulin resistance the same as diabetes?
No. Insulin resistance can exist for years with normal blood sugar. It increases the risk of prediabetes and type 2 diabetes, but not everyone with insulin resistance develops diabetes.
Should I ask for a fasting insulin test?
It is not a routine diagnostic test, and results are hard to interpret on their own. Your doctor may find a combination of the markers above more useful.
Can thin people be insulin resistant?
Yes. Fat around the abdominal organs, inactivity, family history and other factors matter, not just body weight.
Can insulin resistance be reversed?
For many people it improves significantly with activity, nutrition, sleep and weight changes. How much depends on the person.
References
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Insulin resistance and prediabetes. https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance
- Alberti KGMM et al. Harmonizing the metabolic syndrome. Circulation. 2009.
- Diabetes Prevention Program Research Group. New England Journal of Medicine. 2002.
- World Health Organization. Guidelines on physical activity and sedentary behaviour. 2020.
- American Academy of Sleep Medicine and Sleep Research Society. Recommended amount of sleep for a healthy adult.
This article is for general educational purposes only, like a health newsletter. It is not medical advice, diagnosis or treatment, and reading it does not create a doctor and patient relationship. Please speak to your own doctor about your situation. In an emergency, call 10177 or 112, or go to your nearest emergency unit.