Insulin resistance: what it means, who is at risk and how to reduce it

Insulin is a hormone that helps the body use glucose, the sugar in the blood, for energy. In insulin resistance, the insulin the body makes does not work as well as it should, so glucose is not taken up from the blood as efficiently. The NHS describes this as the insulin it makes not working properly, and names it explicitly as insulin resistance in its description of type 2 diabetes.

Insulin resistance is best understood as part of the picture behind prediabetes, type 2 diabetes and some other conditions, rather than as a stand-alone illness. It is something doctors and patients try to reduce by managing risk factors such as weight and physical inactivity.

The NHS explains that when glucose stays too high, complications such as heart disease, kidney disease, stroke or nerve problems may result. That is why identifying risk early matters, even when you feel well.

The NHS lists the people more likely to develop type 2 diabetes, which is the main outcome of long-standing insulin resistance. You may be more at risk if you are:

• White and over 40, or over 25 and from a South Asian, Chinese, Black African or Black Caribbean ethnic background.

• A person with a parent, brother or sister who has type 2 diabetes.

• Overweight and not very physically active.

• A person with a condition that increases risk, such as high blood pressure.

Polyendocrine metabolic ovarian syndrome (PMOS), previously known as polycystic ovary syndrome or PCOS, is one example. The NHS says its cause is unknown but may be to do with hormones such as insulin and testosterone not working properly, that tests can include blood tests for hormone levels and insulin resistance, and that it can increase the risk of type 2 diabetes, high blood pressure, cardiovascular disease and non-alcoholic fatty liver disease. Metformin, a type 2 diabetes medicine, is sometimes used for tiredness and weight problems.

Being overweight is another strong link. The NHS lists type 2 diabetes, heart disease, stroke and high blood pressure among the risks of overweight and obesity, and says losing 5 to 10% of body weight can improve health.

Insulin resistance itself usually causes no symptoms. The NHS says that most people with prediabetes do not have symptoms of type 2 diabetes. When blood glucose rises into the diabetic range, the most common symptoms the NHS lists are feeling very tired, peeing more than usual, feeling thirsty all the time and losing weight without trying to. Others include blurred vision, cuts or wounds taking longer to heal, and itching around the genitals or recurrent thrush.

These can be similar to type 1 diabetes, which usually develops more quickly and is more common in younger people. If you have these symptoms, or are in a higher-risk group, the NHS says to see a GP, because not everyone with type 2 diabetes has symptoms and getting checked is important.

The NHS says type 2 diabetes is diagnosed with a blood test that checks how high your blood glucose levels are, with results usually taking a few days, and that prediabetes means levels are higher than normal but not high enough to diagnose diabetes. Your GP or practice nurse will interpret the results with you.

You can also check your risk yourself with the Know Your Risk tool from Diabetes UK, as the NHS suggests. If you are aged 40 to 74 and have no existing condition, the NHS Health Check gives an overall assessment that includes a diabetes risk assessment, together with your BMI, blood pressure and cholesterol.

There is no single treatment for insulin resistance, but the factors that worsen it are modifiable. For overweight adults the NHS recommends eating fewer calories, a balanced diet with plenty of fruit and vegetables, and 45 to 60 minutes of activity a day, with steady weight loss of 0.5 to 1kg a week. The NHS says it may be possible to prevent type 2 diabetes by losing weight and improving diet.

If you are told you have prediabetes, the NHS says to talk to your care team about how healthier eating, exercise and other lifestyle changes can help prevent type 2 diabetes. Courses such as DESMOND and X-PERT Health are described by the NHS for people with type 2 diabetes who want to learn to manage it.

When blood sugar has already reached the diabetic range, the NHS says type 2 diabetes can be managed with diet and exercise, or with medicines, and that you will have a care team to help with questions about treatment.

In the NHS the route is the GP or practice nurse for a blood test, the NHS Health Check if you are eligible, and referral to education courses or weight management services where appropriate. Women with PMOS may also be seen by gynaecology or endocrinology services.

Some people choose private blood tests or a consultation with a private endocrinologist or dietitian. Whichever route you take, results are best interpreted with your GP so they sit alongside your medical history, and repeat checks should be planned rather than one-off.