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 you have a higher than normal blood sugar level. It's not high enough to be considered type 2 diabetes yet. But without lifestyle changes, adults and children with prediabetes are at high risk to develop type 2 diabetes.

If you have prediabetes, the long-term damage of diabetes — especially to your heart, blood vessels and kidneys — may already be starting. There's good news, however. Progression from prediabetes to type 2 diabetes isn't inevitable.

Eating healthy foods, making physical activity part of your daily routine and staying at a healthy weight can help bring your blood sugar level back to normal. The same lifestyle changes that can help prevent type 2 diabetes in adults might also help bring children's blood sugar levels back to normal.

Products & Services


Prediabetes doesn't usually have any signs or symptoms.

One possible sign of prediabetes is darkened skin on certain parts of the body. Affected areas can include the neck, armpits and groin.

Classic signs and symptoms that suggest you've moved from prediabetes to type 2 diabetes include:

  • Increased thirst
  • Frequent urination
  • Increased hunger
  • Fatigue
  • Blurred vision
  • Numbness or tingling in the feet or hands
  • Frequent infections
  • Slow-healing sores
  • Unintended weight loss

When to see a doctor

See your health care provider if you're concerned about diabetes or if you notice any type 2 diabetes signs or symptoms. Ask your health care provider about blood sugar screening if you have any risk factors for diabetes.

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.


The exact cause of prediabetes is unknown. But family history and genetics appear to play an important role. What is clear is that people with prediabetes don't process sugar (glucose) properly anymore.

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

Insulin is produced by a gland located behind the stomach called the pancreas. Your pancreas sends insulin to your blood when you eat. When your blood sugar level starts to drop, the pancreas slows down the secretion of insulin 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 may not make enough insulin
  • Your cells become resistant to insulin and don't allow as much sugar in

Risk factors

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

  • Weight. Being overweight is a primary risk factor for prediabetes. The more fatty tissue you have — especially inside and between the muscle and skin around your abdomen — the more resistant your cells become to insulin.
  • Waist size. A large waist size can indicate insulin resistance. The risk of insulin resistance goes up for men with waists larger than 40 inches and for women with waists larger than 35 inches.
  • Diet. Eating red meat and processed meat, and drinking sugar-sweetened beverages, is associated with a higher risk of prediabetes.
  • Inactivity. The less active you are, the greater your risk of prediabetes.
  • Age. Although diabetes can develop at any age, the risk of prediabetes increases after age 35.
  • Family history. Your risk of prediabetes increases if you have a parent or sibling with type 2 diabetes.
  • Race or ethnicity. Although it's unclear why, certain people — including Black, Hispanic, American Indian and Asian American people — are more likely to develop prediabetes.
  • Gestational diabetes. If you had diabetes while pregnant (gestational diabetes), you and your child are at higher risk of developing prediabetes.
  • Polycystic ovary syndrome. Women with this common condition — characterized by irregular menstrual periods, excess hair growth and obesity — have a higher risk of prediabetes.
  • Sleep. People with obstructive sleep apnea — a condition that disrupts sleep repeatedly — have an increased risk of insulin resistance. People who are overweight or obese have a higher risk of developing obstructive sleep apnea.
  • Tobacco smoke. Smoking may increase insulin resistance and can increase the risk of type 2 diabetes in people with prediabetes. Smoking also increases your risk of complications from diabetes.

Other conditions associated with an increased 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 your blood

Metabolic syndrome

When certain conditions occur with obesity, they are associated with insulin resistance, and can increase your risk for diabetes — and heart disease and stroke. A combination of three or more of these conditions is often called metabolic syndrome:

  • High blood pressure
  • Low levels of HDL
  • High triglycerides
  • High blood sugar levels
  • Large waist size


Prediabetes has been linked with long-term damage, including to your heart, blood vessels and kidneys, even if you haven't progressed to type 2 diabetes. Prediabetes is also linked to unrecognized (silent) heart attacks.

Prediabetes can progress to type 2 diabetes, which can lead to:

  • High blood pressure
  • High cholesterol
  • Heart disease
  • Stroke
  • Kidney disease
  • Nerve damage
  • Fatty liver disease
  • Eye damage, including loss of vision
  • Amputations


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

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

Nov. 11, 2023
  1. American Diabetes Association. Standards of medical care in diabetes —2021. Diabetes Care. 2020; doi:10. 2337/dc21-Sint.
  2. Prediabetes ⸺ Your chance to prevent type 2 diabetes. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/prediabetes.html. Accessed Oct. 18, 2021.
  3. The surprising truth about prediabetes. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/library/features/truth-about-prediabetes.html. Accessed Oct. 18, 2021.
  4. Diabetes: 12 warning signs that appear on your skin. American Academy of Dermatology Association. https://www.aad.org/public/diseases/a-z/diabetes-warning-signs. Accessed Oct. 22, 2021.
  5. Insulin resistance and prediabetes. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance. Accessed Oct. 18, 2021.
  6. Type 2 diabetes. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/type-2-diabetes. Accessed Oct. 18, 2021.
  7. Diabetes tests and diagnosis. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/diabetes/overview/tests-diagnosis. Accessed Oct. 20, 2021.
  8. Rett K, et al. Understanding prediabetes: Definition, prevalence, burden and treatment options for an emerging disease. Current Medical Research and Opinion. 2019: doi:10.1080/03007995.2019.1601455.
  9. Mahat RK, et al. Health risks and interventions in prediabetes: A review. Diabetes & Metabolic Syndrome: Clinical Research & Reviews. 2019; doi:0.1016/j.dsx.2019.07.041.
  10. Wallace AS, et al. Screening and diagnosis of prediabetes and diabetes in US children and adolescents. Pediatrics. 2020; doi:10.1542/peds.2020-0265.
  11. Magge SN, et al. Evaluation and treatment of prediabetes in youth. Journal of Pediatrics. 2020; doi:10.1016/j.jpeds.2019.12.061.
  12. Physical activity guidelines for Americans. 2nd ed. U.S. Department of Health and Human Services. https://health.gov/our-work/nutrition-physical-activity/physical-activity-guidelines/current-guidelines. Accessed Oct. 18, 2021.
  13. Natural medicines in the clinical management of diabetes. Natural Medicines. https://naturalmedicines.therapeuticresearch.com. Accessed Oct. 19, 2021.
  14. About metabolic syndrome. American Heart Association. https://www.heart.org/en/health-topics/metabolic-syndrome/about-metabolic-syndrome. Accessed Oct. 20, 2021.
  15. Cigarette smoking: A risk factor for type 2 diabetes. U.S. Food and Drug Administration. https://www.fda.gov/tobacco-products/health-effects-tobacco-use/cigarette-smoking-risk-factor-type-2-diabetes. Accessed Oct. 20, 2021.
  16. Polycystic ovary syndrome. OASH Office on Women's Health. https://www.womenshealth.gov/a-z-topics/polycystic-ovary-syndrome. Accessed Oct. 22, 2021.
  17. Castro MR (expert opinion). Mayo Clinic. Oct. 23, 2021.


Associated Procedures

News from Mayo Clinic

Products & Services