What is Insulin Resistance?

Medically reviewed by Carmen Pope, BPharm. Last updated on June 21, 2022.

Insulin resistance is when the cells in your muscles, start ignoring or resisting the signal that the hormone insulin sends which tells these cells to uptake glucose (sugar) from the blood. Glucose is the body’s main source of energy, and we get it from grains, fruit, vegetables, and other foods that break down into carbohydrates. One in three Americans is reported to have insulin resistance. Insulin resistance may also be called low insulin sensitivity.

What are the signs or symptoms of insulin resistance?

A large belly or waist is the most common symptom of insulin resistance. People who carry a lot of weight around their waist, for example, a waist size of 35 inches or more (women) or 40 inches (men), or even less if you are of Southeast Asian, Chinese, or Japanese descent (31.5 inches for women and 35.5 inches for men), are more likely to have insulin resistance and the metabolic syndrome.

Dark skin patches are common in people with severe insulin resistance. These patches may be visible on the back of your neck, elbows, knuckles, or armpits. The medical term for these patches of skin discoloration is acanthosis nigricans.

Who is at risk of insulin resistance?

You are at a higher risk of developing insulin resistance if you are overweight and don't do much exercise. Other risk factors include older age, genetics (people from a South Asian background are more likely to develop insulin resistance from an early age), smoking, and maybe not getting enough sleep.

Dyslipidemia is another risk factor, and people with high triglycerides (150 mg/dL or more) or low HDL levels (below 50 mg/dL for women or below 40 mg/dL for men), even those taking medication, are at risk of metabolic syndrome which is linked with insulin resistance.

High blood pressure readings of more than 130/85 mmHg or higher, as well as high fasting blood sugar readings (more than 100 mg/dL [prediabetes]) also increase your risk.

How does insulin resistance relate to diabetes?

If our cells do not respond properly to insulin, then glucose remains in the blood, where it can't be used as an energy source by cells. Our body tries to fight back by ramping up insulin production by special cells in the pancreas called beta cells. But there is only so much insulin our pancreas can make, and within a few years, our beta cells wear out, and produce very little, if any, insulin.

Blood sugar levels start to rise, and testing reveals prediabetes or type 2 diabetes. Prediabetes is when you have higher than normal blood glucose levels, but they are not yet high enough to be considered type 2 diabetes. Diabetes is a long-term condition that occurs when the pancreas is no longer able to make insulin at all or the body cannot make use of the little insulin that is made. People with diabetes may need to inject themselves with man-made insulin.

What health conditions are associated with insulin resistance and diabetes?

Insulin resistance can develop into prediabetes and diabetes and increase your risk of having a heart attack, stroke, cancer, and several other serious conditions.

Insulin resistance doubles your chances of having a heart attack or stroke and these are three times more likely to be deadly. This is because consistently high blood sugar levels create inflammation which damages cells, increasing the risk of cardiovascular disease.

High insulin levels also appear to fuel the growth of some cancers, with cancers of the bladder, breast, colon, cervix, pancreas, prostate, and uterus being more common in people with insulin resistance.

Insulin resistance is also associated with a higher risk of dementia, including Alzheimer’s Disease, and non-alcoholic fatty liver disease (NAFLD) (this is a build-up of fat in the liver not caused by alcohol).

How are insulin resistance and the metabolic syndrome linked?

Experts believe that insulin resistance in addition to physical inactivity is a major reason behind the development of the metabolic syndrome. Metabolic syndrome is a cluster of risk factors that includes obesity, insulin resistance, high blood pressure, and high cholesterol (dyslipidemia), and people with this deadly quartet are at a very high risk of death.

How can you prevent or reverse insulin resistance?

The best way to prevent or reverse insulin resistance is to exercise more AND eat a healthy diet. If you do both and lose 10% of your body weight, then studies have shown you can improve your insulin sensitivity by almost 80%. If you only diet without improving your physical activity, then you only stand to improve your insulin sensitivity by approximately 38%.

Make sure you get a good night’s sleep, every night. One night of sleep deprivation contributed to insulin resistance as much as 6 months’ worth of high-fat foods in one study.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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