Overview

What is insulin resistance? A Mayo Clinic expert explains

Learn about insulin resistance from Eleanna De Filippis, M.D., Ph.D., an endocrinologist at Mayo Clinic.

Hello. I'm Dr. Eleanna De Filippis, an endocrinologist at Mayo Clinic. In this video, we'll cover the basics of insulin resistance. What is it? Who gets it? The symptoms, diagnosis and treatment. Whether you're looking for answers for yourself or someone you love, we're here to give you the best information available. To understand insulin resistance, often referred to as prediabetes, let's first talk about what insulin does. When you eat food, your body converts that food into dietary sugars. Insulin is a hormone released by the pancreas that tells your cells to open up to that sugar and convert it into energy. With insulin resistance, the cells don't react, and don't open up, resulting in excessive sugar in the blood. Over time, the pancreas keeps trying to regulate the blood sugar, producing more and more insulin until it wears out and can't produce large amounts of insulin anymore. As a result, blood sugar levels increase to the point of being in the diabetic range.

Who gets it?

Anyone can become insulin-resistant. In particular, people with excess weight are at a higher risk, compared to the general population. Risk is further increased with a family history of type two diabetes, age over 45, African, Latino or Native American ancestry, smoking, and certain medications, including steroids, anti-psychotics, and HIV medication. There are other medical conditions associated with insulin resistance, like obstructive sleep apnea, fatty liver disease, polycystic ovarian syndrome, also known as PCOS, Cushing's syndrome, and lipodystrophy syndromes. Lipodystrophy syndromes are conditions that cause abnormal fat loss. So carrying either too much or not enough fat tissue in your body can be associated with insulin resistance.

What are the symptoms?

Very often people with insulin resistance don't have any symptoms at all. It is usually picked up by their doctor during an annual health exam or routine blood work. There are some signs of insulin resistance that your doctor may look for. These includes a waistline over 40 inches in men, and a waistline over 35 inches in women. Skin tags or patches of dark velvety skin called acanthosis nigricans. A blood pressure reading of 130 over 80 or higher. A fasting glucose level equal or above 100 milligrams per deciliter. Or a blood sugar level equal or above 140 milligrams per deciliter two hours after a glucose load test. An A1C between 5.7% and 6.3%. A fasting triglycerides level over 150 milligram per deciliter. And an HDL cholesterol level under 40 milligrams per deciliter in men, and an HDL cholesterol level under 50 milligrams per deciliter in women.

How is it diagnosed?

If your doctor spots these symptoms, they may follow up with a physical exam and a variety of blood tests that measure the levels of glucose, or sugar, in your blood and/or your tolerance to that glucose. Or more recently, a blood test called hemoglobin glycosylated A1C, often simply referred to as A1C.

How is it treated?

Reversing insulin resistance and preventing type two diabetes is possible through lifestyle changes, medication, or sometimes both. Healthy bodies come in different shapes and sizes. Losing weight through drastic means can be dangerous and counterproductive. Instead, get ideas from a doctor or a nutritionist about ways to incorporate healthy foods like fruits, vegetables, nuts, beans, and lean proteins into your meals. Also, consider incorporating exercise and movement into your day-to-day life in ways that make you feel good.

What now?

Even though permanently defeating insulin resistance isn't always possible, you can help your body to be more receptive to insulin. Listen to your body, reduce stress, give it the nutrition and activity it desires. If you'd like to learn even more about insulin resistance, watch our other related videos or visit mayoclinic.org. We wish you well.

Prediabetes means having a higher than typical blood sugar level. It's not high enough to be type 2 diabetes yet. But without lifestyle changes, adults and children with prediabetes are at high risk of getting type 2 diabetes.

People with prediabetes may have some of the long-term damage to the heart, blood vessels and kidneys that diabetes causes. But the risk gets much higher if they get type 2 diabetes. There are ways to keep prediabetes from becoming type 2 diabetes.

Eating healthy foods, being physically active and staying at a healthy weight can help bring your blood sugar level back down. The same lifestyle changes that can help prevent type 2 diabetes in adults also may help children.

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Symptoms

Prediabetes often has no clear symptoms.

One possible sign of prediabetes is darkened skin on certain parts of the body. Affected areas can include the neck, armpits and groin. Darkened skin may look dark brown or black on brown or Black skin and light brown or tan on white skin.

Symptoms that may mean you've moved from prediabetes to type 2 diabetes include:

  • Greater thirst.
  • Urinating more often.
  • Greater hunger.
  • Tiredness.
  • Blurred vision.
  • Numbness or tingling in the feet or hands.
  • Repeat infections.
  • Slow-healing sores.
  • Weight loss without trying.

When to see a doctor

See your healthcare professional if you're worried about diabetes or if you have any type 2 diabetes symptoms. Ask your healthcare professional about blood sugar screening if you have risk factors for diabetes.

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Causes

Experts don't know the exact cause of prediabetes. But family history and genes seem important. What is clear is that people with prediabetes have trouble managing blood sugar, also called glucose.

Most of the glucose in your body comes from the food you eat. When you digest food, sugar enters your bloodstream. Insulin allows sugar to enter your cells and lowers the amount of sugar in your blood.

A gland that sits behind the stomach called the pancreas makes insulin. Your pancreas sends insulin to your blood when you eat. When your blood sugar level starts to drop, the pancreas slows down the amount of insulin that goes into the blood.

When you have prediabetes, this process doesn't work as well. As a result, instead of fueling your cells, sugar builds up in your bloodstream. This can happen because:

  • Your pancreas doesn't make enough insulin.
  • Your cells resist the insulin and don't let in as much sugar. This is called insulin resistance.

Risk factors

The same factors that raise the risk of getting type 2 diabetes also raise the risk of prediabetes. These factors include:

  • Weight. Being overweight is a main risk factor for prediabetes. The more fatty tissue your body has, the more your cells resist insulin. This is mainly true for fatty tissue inside and between the muscle and skin around your belly.
  • Waist size. A large waist may mean insulin resistance. The risk of insulin resistance goes up for people assigned male at birth with waists larger than 40 inches and for people assigned female at birth with waists larger than 35 inches.
  • Diet. Diets high in red meats, processed foods, saturated fat and sugar are linked with a higher risk of prediabetes.
  • Not being active. The less active you are, the higher your risk of prediabetes.
  • Age. Although diabetes can happen at any age, the risk of prediabetes goes up after age 35.
  • Family history. Your risk of prediabetes rises if you have a parent or sibling with type 2 diabetes.
  • Race or ethnicity. It's not clear why, but certain people are more likely to get prediabetes. In the United States, these include Black, Hispanic, American Indian and Asian American people.
  • Gestational diabetes. If you had diabetes while pregnant, also called gestational diabetes, you and your child are at higher risk of getting prediabetes. Low birth weight babies also have a higher risk.
  • Polycystic ovary syndrome. This condition involves having menstrual periods that aren't regular, excess hair growth and obesity. It raises the risk of prediabetes.
  • Sleep. People with obstructive sleep apnea are at higher risk of insulin resistance. Obstructive sleep apnea is a condition that disrupts sleep throughout the night. People who are overweight or people with obesity have a higher risk of getting obstructive sleep apnea.
  • Tobacco smoke. Smoking may raise insulin resistance and the risk of type 2 diabetes in people with prediabetes. Smoking also raises the risk of complications from diabetes.

Other conditions linked with a higher risk of prediabetes include:

  • High blood pressure.
  • Low levels of high-density lipoprotein (HDL) cholesterol, the "good" cholesterol.
  • High levels of triglycerides, a type of fat in the blood.

Metabolic syndrome

If you have certain conditions with obesity, you may have a higher risk of diabetes, heart disease and stroke. If you have three or more of these conditions, it's often called metabolic syndrome:

  • High blood pressure.
  • Low levels of high-density lipoprotein (HDL) cholesterol, the "good" cholesterol.
  • High levels of triglycerides, a type of fat in the blood.
  • High blood sugar levels.
  • Large waist size.

Complications

Prediabetes has been linked with long-term damage, including to your heart, blood vessels and kidneys. This is true even before you get type 2 diabetes. Prediabetes also is linked to what's called silent heart attacks. Silent heart attacks have few symptoms or have symptoms that aren't like those of a heart attack.

Prediabetes can go on to be type 2 diabetes, which can lead to:

  • High blood pressure.
  • High cholesterol.
  • Heart issues.
  • Stroke.
  • Kidney issues.
  • Nerve damage.
  • Fatty liver disease.
  • Eye damage, including loss of vision.
  • Surgery to remove a part of the body, called an amputation.

Prevention

Healthy lifestyle choices can help you prevent prediabetes and its move to type 2 diabetes, even if diabetes runs in your family. These include:

  • Eating healthy foods.
  • Getting active.
  • Losing excess weight.
  • Managing your blood pressure and cholesterol.
  • Not smoking.

Sept. 10, 2026
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