Insulin resistance is when your cells stop responding to insulin. So sugar builds up in the bloodstream, and the pancreas pumps out even more insulin to make up for it. It is the main cause of type 2 diabetes. Weight loss, dietary change and exercise reduce it.
Insulin is a vital hormone that controls how much sugar is in our bodies. In a nutshell, it pulls extra glucose out of the blood through a process known as glycogenesis.
However, problems with insulin are at the heart of many medical conditions. Insulin resistance occurs when your cells stop responding to insulin. This means insulin cannot do its job, so sugar builds up in the bloodstream. About 100 million Americans are affected by insulin resistance. Luckily, changes in diet and lifestyle can dramatically improve it.
This article explains all you need to know about insulin and insulin resistance.
What Is Insulin?
Insulin is a hormone made by beta cells in the pancreas. Its main job is to control how much glucose moves through your bloodstream. But it also affects fat and protein metabolism (how your body uses fat and protein). When you eat a slice of bread, which definitely contains carbs, the sugar in your blood goes up. So the beta cells in your pancreas are prompted to make insulin. The insulin is released into your bloodstream. There it takes the sugar and stores it in cells. This lowers blood sugar.
However, cells sometimes become less sensitive to insulin. When this happens, sugar begins to build up in the bloodstream. Your pancreas makes even more insulin to lower the blood sugar levels. This leads to high insulin levels in your blood, which is called hyperinsulinemia.
Diabetes type 2 occurs when your cells become more and more resistant to insulin. As a result, both insulin and blood sugar levels rise. If this goes on for long, your beta cells may become damaged. That leads to less insulin being made.
Insulin resistance is the main cause of type 2 diabetes.
What About Insulin Sensitivity?
Insulin sensitivity is the opposite of insulin resistance. If you have insulin resistance, you also have low insulin sensitivity. Insulin resistance harms your health. Insulin sensitivity is good for it.
What Causes Insulin Resistance?
Insulin resistance is caused by many factors.
A number of studies have shown that high amounts of free fatty acids in your blood can cause insulin resistance. This is caused by eating too many calories. Being overweight or obese is also linked to insulin resistance. Visceral fat (the fat packed around your organs) mostly builds up around your waist. It can release free fatty acids into your blood and trigger inflammation. However, even people with moderate weight can develop insulin resistance, possibly due to genetic predisposition (traits they were born with).
Other possible causes of insulin resistance include:
- High sugar diet. Artificial sugars have been linked to inflammation and insulin resistance.
- Inactivity. Regular exercise can reduce insulin resistance because it helps you lose weight.
- Gut microbiota. Upsetting the mix of bacteria in your gut can cause inflammation and insulin resistance.
- Genetic factors: African American, Hispanic, and Asian peoples are at higher risk for insulin resistance.
What Are The Complications Of Insulin Resistance?
Insulin resistance is the precursor (the early stage that comes before) for diabetes type 2 and metabolic syndrome. Metabolic syndrome is a group of risk factors associated with type 2 diabetes and heart disease.
By the time a person is diagnosed with type 2 diabetes, they are likely to have developed chronic (long-lasting) insulin resistance. It is estimated that by then, 50% of the cells that make insulin may have stopped working. So the person is not only resistant to insulin. They also cannot make enough of it.
Insulin resistance is also strongly associated with heart disease, which is the leading cause of death in the US.
Other diseases linked to insulin resistance include:
- Non-alcoholic fatty liver disease (NAFLD)
- Cancer
- Polycystic ovarian syndrome (PCOS)
- Alzheimer’s disease
How To Reduce Insulin Resistance
Weight loss is one of the most effective ways to reduce insulin resistance. Drastic changes in diet are also needed, so you eat more of the good foods and less of the harmful ones. Exercise also helps you shed extra weight and stay healthy. Lastly, dropping harmful habits such as smoking and heavy drinking also plays a significant role.
- Get regular exercise, such as brisk walking or jogging, for 30 minutes each day.
- Lose belly fat
- Stop smoking
- Eat less artificial sugar, such as from artificially sweetened drinks
- Eat more omega-3 fatty acids
For more on how diet changes improve insulin sensitivity, read our article on foods that improve insulin sensitivity.
The bottom line
Insulin resistance is behind a number of chronic health problems. Often it can go unnoticed for years without causing alarm. When insulin resistance is not caught early enough, it is likely to wreck a person’s health. Luckily, a number of things can be done to prevent insulin resistance or stop it from getting worse. If insulin resistance can be prevented, we will definitely have millions of people living healthier, fuller lives that are free of disease.
Related reading
References
1. NCBI (2005): Dose-response effect of elevated plasma free fatty acid on insulin signaling. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/15919784
2. CDC (2017): New CDC report: More than 100 million Americans have diabetes or prediabetes. Retrieved from https://www.cdc.gov/media/releases/2017/p0718-diabetes-report.html
3. NCBI (2005): Dose-response effect of elevated plasma free fatty acid on insulin signaling. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/15919784
4. NCBI (2013): The Role of Gut Microbiota on Insulin Resistance. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3705322/
Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP
Interventional pain physician, addiction medicine specialist and obesity medicine diplomate.
Licensed in Missouri and Illinois.
Last reviewed June 18, 2026
