Insulin Resistance: Causes, Signs, and How to Improve It

Gloved hand placing blood sample tubes in a rack for lab testing — Photo: U.S. Air Force photo by Senior Airman Kevin Dunkleberger via Wikimedia Commons (Public domain). Image credits

Last reviewed: October 9, 2026 · Sources: CDC, NIH/NIDDK, American Diabetes Association

Insulin resistance is at the root of prediabetes and type 2 diabetes, and it is linked with heart disease, fatty liver disease, and other health problems. Yet many people have never heard of it or don't know they have it. The encouraging news is that insulin resistance can often be improved with changes in activity, eating, sleep, and weight. This guide explains what insulin resistance is, what causes it, how it is identified, and what you can do about it.

What is insulin resistance?

Insulin is a hormone made by the pancreas that helps glucose move from the blood into cells, especially in muscles, fat, and the liver. According to NIDDK, insulin resistance occurs when cells in these tissues don't respond well to insulin and can't easily take up glucose from the blood. To compensate, the pancreas makes more insulin. As long as the pancreas can keep up, blood glucose stays in a healthy range. Over time, if the beta cells can't make enough extra insulin, blood glucose rises, leading to prediabetes and type 2 diabetes.

The CDC describes it this way: insulin acts like a key to let blood sugar into cells; with prediabetes, cells don't respond normally to insulin, the pancreas makes more insulin, and eventually it can't keep up.

What causes insulin resistance?

Researchers don't fully understand all the causes, but several factors are strongly linked:

Excess body fat, especially around the abdomen and in organs like the liver. NIDDK identifies excess weight and physical inactivity as major contributors.
Physical inactivity. Muscles that are regularly active respond better to insulin.
Genetics and family history.
Age. The risk increases as people get older.
Certain medicines, such as glucocorticoids (steroids), some antipsychotics, and some HIV medicines.
Hormonal conditions, such as polycystic ovary syndrome (PCOS) and Cushing's syndrome.
Poor sleep and sleep apnea. See sleep and diabetes.
Chronic stress, through stress hormones. See stress and blood sugar.
Smoking. See diabetes and smoking.
Pregnancy, which naturally increases insulin resistance; this can lead to gestational diabetes. See gestational diabetes.

Some racial and ethnic groups have a higher risk of insulin resistance and type 2 diabetes, including African American, Hispanic/Latino, American Indian, Alaska Native, Pacific Islander, and some Asian American people.

Conditions linked with insulin resistance

Insulin resistance is associated with:

Prediabetes and type 2 diabetes. See prediabetes and type 2 diabetes.
High blood pressure
Abnormal cholesterol and high triglycerides
Heart disease and stroke. See heart health.
Metabolic dysfunction-associated steatotic liver disease (formerly called nonalcoholic fatty liver disease)
Polycystic ovary syndrome. See diabetes symptoms in women.

A cluster of these conditions, including abdominal obesity, high blood pressure, high triglycerides, low HDL cholesterol, and high fasting glucose, is often called metabolic syndrome.

Signs and symptoms

Insulin resistance usually has no symptoms. Some people have visible signs:

Acanthosis nigricans: darkened, velvety skin on the back of the neck, armpits, or groin. See diabetes and skin conditions.
Skin tags.
A larger waist size.

Because symptoms are rare, people often learn about insulin resistance only when blood tests show prediabetes or diabetes.

How insulin resistance is identified

There is no single routine test used in everyday practice to measure insulin resistance directly. Instead, providers look at risk factors and common blood tests:

A1C, fasting plasma glucose, or oral glucose tolerance test to check for prediabetes or diabetes. See A1C and blood sugar targets.
Cholesterol and triglyceride levels.
Blood pressure.
Waist circumference and weight.

Research studies may use specialized tests or calculations based on fasting insulin and glucose, but these are not usually needed to start healthy changes. If you have risk factors, ask your provider about testing for prediabetes and diabetes.

How to improve insulin resistance

The steps that help are the same ones that prevent type 2 diabetes.

Be physically active

Physical activity is one of the most powerful tools. During and after exercise, muscles use glucose more effectively, and regular activity improves insulin sensitivity over time. The CDC recommends at least 150 minutes of moderate-intensity activity a week plus muscle-strengthening on two or more days, as described in its adult activity overview. Strength training builds muscle, which helps use glucose. Breaking up long periods of sitting also helps. See exercise and diabetes.

Lose weight if you have overweight

The CDC notes that losing around 5% to 7% of body weight, about 10 to 14 pounds for a 200-pound person, along with regular activity, can lower the risk of type 2 diabetes for people with prediabetes. Losing fat around the abdomen and liver is particularly helpful. See weight and diabetes.

Eat for insulin sensitivity

Fill half your plate with nonstarchy vegetables.
Choose high-fiber whole grains, beans, and lentils. See fiber and diabetes.
Limit sugary drinks, refined grains, and highly processed foods.
Include healthy fats from nuts, seeds, olive oil, and fish.
Watch portion sizes.

See diabetes-friendly eating basics.

Sleep well

Aim for at least 7 hours of sleep, and get evaluated for sleep apnea if you snore loudly or are sleepy during the day.

Manage stress and stop smoking

Both chronic stress and smoking contribute to insulin resistance.

Medicines

For some people, a provider may recommend medicines. Metformin, for example, can improve how the body responds to insulin and is sometimes used for people at high risk of type 2 diabetes. See metformin and common diabetes medications.

Join a lifestyle change program

The CDC-led National Diabetes Prevention Program helps people with prediabetes make lasting changes. The CDC states it can lower the risk of type 2 diabetes by 58% (71% for people over 60).

Frequently asked questions

Can insulin resistance be reversed?

Insulin sensitivity can often be improved substantially with activity, weight loss, and healthy eating. Some people can bring their glucose back to the normal range.

How quickly does exercise help?

A single session of activity can improve how muscles use glucose for a period afterward, and regular activity builds lasting benefits.

Do I need a special diet?

No single diet is required. Eating patterns that emphasize vegetables, fiber, and whole foods and limit sugary drinks and refined carbohydrates help.

Can thin people have insulin resistance?

Yes. Genetics, inactivity, fat around organs, and other factors can cause insulin resistance at any weight.

Is insulin resistance the same as prediabetes?

Not exactly. Insulin resistance can exist for years while glucose stays normal because the pancreas makes extra insulin. Prediabetes means glucose has risen above normal but not yet to the diabetes range.

Do people with type 1 diabetes have insulin resistance?

They can. People with type 1 diabetes can also develop insulin resistance, especially with weight gain or inactivity, and may then need more insulin. Some people describe this combination as having features of both types.

Does insulin resistance cause weight gain?

Insulin resistance and weight are closely connected, and each can make the other worse. High insulin levels are linked with fat storage, and excess body fat increases insulin resistance. Regular activity and healthy eating can help break this cycle.

Where can I find more reliable information?

Trusted sources include the CDC, NIDDK, MedlinePlus, and the American Diabetes Association. Be cautious with social media posts or products that promise quick fixes, and check new information with your care team before making changes.

Key takeaways

Insulin resistance means cells don't respond well to insulin, so the pancreas must make more to keep glucose normal.
It underlies prediabetes and type 2 diabetes and is linked to heart disease, fatty liver, and PCOS.
It usually has no symptoms; darkened skin in body folds can be a sign.
Activity, modest weight loss, healthy eating, good sleep, and not smoking improve insulin sensitivity.

Sources

Links to the sources cited above appear in the text. We rely on the Centers for Disease Control and Prevention (CDC), the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and the American Diabetes Association (ADA).

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