What Is Insulin Resistance?

Impaired glucose tolerance can be a precursor to diabetes

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Insulin Resistance
Insulin Resistance is Improved by Exercise and Eating Right. webphotographeer E+/Getty Images

Insulin resistance is a condition in which your body does not respond to insulin as it should. This condition, sometimes referred to as impaired glucose tolerance, often occurs before prediabetes or metabolic syndrome develops. If left untreated, long-term complications can include type 2 diabetes, heart disease, and vascular disease. Insulin resistance is usually recognized between the ages of 40 to 60, but it can begin at younger or older ages as well. It is often associated with higher than average weight, high triglyceride levels, and high blood pressure.

Insulin and Blood Sugar

Normally, insulin helps cells in the liver and muscles, as well as fat cells, take up glucose. It activates a protein, GLUT4 to bind to glucose and allows it into the cell so that it can be used for energy.

When insulin is released by the pancreas after we eat, this burst of insulin in the blood is temporary, and quickly declines so that we do not become hypoglycemic (too low in sugar).

With insulin resistance, the body does not respond to insulin—a hormone that helps store glucose (sugar molecules)—despite the fact that enough is produced by the pancreas. When this occurs, the body loses the ability to properly store glucose, the fundamental component of all dietary carbohydrates.

If you have insulin resistance, you may begin to release higher amounts of insulin in an effort to stabilize your blood glucose. Over time, this results in a condition called hyperinsulinemia, in which there is too much insulin in the blood. Hyperinsulinemia makes it more difficult for the body to use stored fat for energy.

Symptoms

Generally, insulin resistance does not cause obvious symptoms, although some people may complain of fatigue.

Pre-diabetes and metabolic syndrome, which may develop in association with insulin resistance, can cause several signs and symptoms, including:

Causes

Insulin resistance is associated with a number of risk factors, but the exact cause is not completely clear. Genetics, being over age 45, and a lack of regular physical activity are believed to contribute to insulin resistance. There is a higher incidence among people of African American, Native American, Latino, and Asian descent.

Other associated factors include weight gain, hypertension, high cholesterol levels, cardiovascular disease, polycystic ovary disease (PCOS), and gestational diabetes, and the relationships between insulin resistance and these factors are complicated because they can exacerbate and be exacerbated by the concern.

Diagnosis

Insulin resistance is a clinical diagnosis, and there is not a reliable diagnostic test that can identify it. Testing actual insulin levels is not a standardized or validated way to know whether you have insulin resistance or not, although this is among the methods used in research studies.

Your medical history, symptoms, and several diagnostic tests can be used together to help your doctors determine whether you have insulin resistance:

  • Fasting blood glucose test: A fasting a blood glucose level between 100 mg/dl and 125 mg/dl is typical of those who are insulin resistant. If your fasting blood glucose reaches 100 mg/dl, you will be diagnosed with prediabetes, and if it reaches 126, diabetes.
  • Oral glucose tolerance test: This test requires that you abstain from eating and drinking for 12 hours before the test. You will have your blood sugar checked, drink a sugary fluid, and have your blood glucose tested again after time has passed. In general, a blood glucose over 140 mg/dl after three hours is suggestive of pre-diabetes or diabetes, and there may be a correlation between high blood glucose levels and insulin resistance.
  • Hemoglobin A1C test: This test measures your average glucose level over the past two to three months. A normal level is between 4 percent and 5.6 percent; a level between 5.7 percent and 6.4 percent is consistent with prediabetes; and a level of 6.5 percent or above is typical of diabetes. Here too, there is not a range that is diagnostic of insulin resistance, but high levels, in consideration of risk factors and symptoms, are suggestive of the diagnosis.

    Remember that blood tests that measure your glucose levels can add to the overall clinical picture, but they can't be used to confirm or rule out the diagnosis. In addition, there is a chance that these levels may be normal in people with early insulin resistance.

    A blood glucose test is routine at your yearly physical examination and may be done at other times if you have symptoms or risk factors for diabetes.

    Treatment

    Insulin resistance and pre-diabetes are both highly predictive of diabetes. If you have been diagnosed with insulin resistance, you can take some action to prevent your condition from advancing in this way. Insulin resistance itself is not treatable, as there is no known way to make your cells more responsive to insulin. However, there are effective strategies that can prevent or delay the onset of diabetes, and make it less severe if you do develop it.

    Recommendations include:

    • Weight loss: If you are overweight, try to reach a healthy weight. Though this is more challenging if you have insulin resistance, it's worth the effort.
    • Exercise: Regular exercise is believed to help your body's metabolism, which can prevent alterations such as insulin resistance.
    • Try a recommended diet: While a low-fat diet was recommended for reducing insulin resistance in the past, the Mediterranean diet and DASH diet—which incorporate healthy fats—are instead favored today. Both emphasize fruits, vegetables, nuts, and whole grains and limit meat, among other things.
    • Taking medications as needed: If you have high blood pressure or high cholesterol levels, you may need medication to control it.

    A Word From Verywell

    Insulin resistance is becoming more common, and about 10 percent of young adults fit the criteria for metabolic syndrome; 44 percent of adults in the over-60 age group do so as well.

    Insulin resistance is considered a very early sign that you could be at risk for diabetes, which sets the stage for a number of serious health complications. If you have insulin resistance, take it as a message from your body that it's time to take steps to improve your health. Addressing this condition early on can help protect you from its risks.

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