An Overview of Insulin Resistance

This condition is a precursor to type 2 diabetes

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Insulin resistance, which is also referred to as impaired glucose tolerance, is a condition in which your body does not respond to insulin as it should. It can progress to prediabetes or metabolic syndrome. If left untreated, long-term complications include type 2 diabetes, heart disease, and vascular disease.

Insulin resistance is usually diagnosed between the ages of 40 and 60, but it can begin at younger or older ages as well. It is often associated with being overweight, high triglyceride fat levels, and high blood pressure.

Symptoms

Generally, insulin resistance develops slowly and does not cause obvious symptoms. It can make you feel tired and low in energy, but since most people blame their fatigue on other factors (e.g., lack of sleep), insulin resistance can go unnoticed for years.

Prediabetes and metabolic syndrome can produce several signs and symptoms due to the effects of chronically elevated blood sugar on the body. There is not necessarily a strict cutoff between insulin resistance and prediabetes, and many of the physical effects and long-term complications overlap.

Signs and symptoms of metabolic syndrome and prediabetes include:

  • Frequent urination
  • Excessive thirst
  • Dark, dry patches of skin on the groin, armpits, or back of the neck, known as acanthosis nigricans
  • Weight gain
  • High triglyceride levels and low HDL (good cholesterol)
  • High blood pressure
  • Heart disease

You may have some of these symptoms if you have insulin resistance, but it is more likely that you will not experience any noticeable effects at all. Nevertheless, these are important warning signs that you could be at risk of diabetes, so you should be sure to discuss them with your medical team if they arise.

Causes

Insulin resistance is associated with a number of risk factors, but the exact cause is not completely clear. There is a higher incidence among people of African American, Native American, Latino, and Asian descent.

A hereditary predisposition, advancing age, being overweight, hypertension, and a lack of regular physical activity are believed to contribute to insulin resistance. Other associated factors include high cholesterol levels, cardiovascular disease, polycystic ovary disease (PCOS), and a history of gestational diabetes.

The relationship between insulin resistance and its risk factors is complicated because they can exacerbate and be exacerbated by one another.

Insulin and Blood Sugar

Insulin is a hormone released by the pancreas within a few minutes after we eat. Normally, this hormone helps our bodies store glucose, sugar that is used for energy. Insulin works by activating a protein, GLUT4, to bind to glucose, which allows the sugar to enter into the liver, muscle, and fat cells.

If you have insulin resistance, your pancreas will release enough insulin, but your body will not adequately respond to the hormone. As a result, you may have less energy and your blood glucose levels may increase.

Often, with insulin resistance, the pancreas begins to release higher amounts of insulin to stabilize blood glucose. Over time, this results in hyperinsulinemia, which is too much insulin in the blood. Hyperinsulinemia does not effectively lower glucose; instead, it makes it more difficult for the body to use stored energy.

Diagnosis

Insulin resistance is a clinical diagnosis that relies on your medical history, overall health, physical examination, and your risk factors. There is not a diagnostic test that can verify it or rule it out.

Several diagnostic tests can be helpful if you have risk factors for insulin resistance, including:

  • Fasting blood glucose test: A fasting a blood glucose level between 100 mg/dl and 125 mg/dl is typical with insulin resistance. If your fasting blood glucose reaches 100 mg/dl, you will be diagnosed with prediabetes, and if it reaches 126, this means that you have diabetes. A fasting 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.
  • Oral glucose tolerance test: This evaluation 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 a few hours. In general, blood glucose over 140 mg/dl after three hours is suggestive of pre-diabetes or diabetes. There may be a correlation between high blood glucose levels during an oral glucose tolerance test and insulin resistance.
  • Hemoglobin A1C test: This test measures your average glucose level over the previous 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 a high level—in consideration of risk factors and symptoms—is suggestive of the diagnosis.

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 with insulin resistance.

Testing 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.

Treatment

Insulin resistance and prediabetes are both highly predictive of diabetes. If you have been diagnosed with insulin resistance, you can take some action to prevent your condition from worsening.

Lifestyle

The key lifestyle changes that are recommended for so many conditions, and general health and wellness, apply here as well:

  • Weight loss: Maintaining a healthy weight is one of the ways to reduce the effects and progression of insulin resistance. Weight loss can be more challenging if you have insulin resistance because the condition can increase your propensity for weight gain, but your efforts are worthwhile.
  • Exercise: Regular exercise helps the body's metabolism, which can prevent metabolic alterations such as insulin resistance.
  • Diet: Most experts recommend the Mediterranean diet or the DASH diet as good approaches to manage insulin resistance. Both diets emphasize healthy fats, fruits, vegetables, nuts, whole grains, and lean meat.

Medication

If you have insulin resistance, you may need medical treatment for your hypertension, heart disease, or high cholesterol, rather than treatment that addresses your insulin and blood sugar levels.

Medications used for the treatment of type 2 diabetes have been prescribed for insulin resistance, although evidence regarding their effectiveness in controlling the disorder is scant.

Metformin makes the body more sensitive to insulin and is used for the treatment of diabetes and often for prediabetic conditions such as insulin resistance.

Thiazolidinediones (also called glitazones), including Avandia (rosiglitazone) and Actos (pioglitazone), are medications that improve the body's response to insulin and are prescribed for type 2 diabetes. They are sometimes used for the management of insulin resistance even without a diagnosis of diabetes.

Keep in mind that all medications have side effects. For this reason, a diagnosis of insulin resistance does not necessarily mean that you need to take prescription medication. You and your doctor will need to weigh the pros and cons of this treatment option.

Natural Therapies

Because diet is so closely associated with insulin and glucose, many herbs and supplements have been considered as possible modifiers of insulin resistance.

However, there is no evidence that supplements can control, reverse, or prevent the progression of insulin resistance.

A Word From Verywell

Insulin resistance is becoming more common among adults of all ages. It 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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