Blood Glucose

Insulin Resistance

January 11, 2017   /
Author: 
Elaine M. Hinzey, RD, LDN

What is insulin?
Insulin is a hormone produced by the beta cells in the pancreas. Insulin has many roles in metabolism of carbohydrates, proteins, and lipids.

What is insulin resistance?
People who are insulin resistant often are making enough insulin, but the insulin is unable to get into the cells to do its job, and the pancreas tries to compensate by pumping out more and more insulin. Once the pancreas is unable to keep up with the demand for insulin, diabetes develops. Some people are insulin resistant for years, preceding the diagnosis of diabetes.

What are risk factors for developing insulin resistance?
The risk factors include:

  • Overweight (the strongest risk factor)
  • Latino, African American, Native American, Alaska Native, Pacific Islander, or Asian ethnicity
  • Physical and emotional stress
  • Long-term use of steroids
  • Pregnancy for some women
  • High intake of refined grains/low intake of whole grains
  • Smoking
  • Meeting the criteria for metabolic syndrome (having any three of the following):
    • Waist measurement of 40″ or more for men and 35″ or more for women
    • Triglyceride levels of 150 milligrams (mg)/deciliter (dL) or above or taking medication for elevated triglyceride levels
    • High-density lipoprotein (HDL), or “good” cholesterol level below 40 mg/dL for men and below 50 mg/dL for women, or taking medication for low HDL levels
    • Blood pressure levels of 130/85 or above, or taking medication for elevated blood pressure levels
    • Fasting blood glucose levels of 100 mg/dL or above, or taking medication for elevated blood glucose levels
  • Older than 40 years of age
  • Sedentary lifestyle

In addition, scientists have identified several genes associated with development of insulin resistance and diabetes.

What other physical conditions result from insulin resistance?
The following physical conditions can result from insulin resistance:

  • Arteriosclerosis
  • Polycystic ovary syndrome and hyperandrogenism
  • Reproductive abnormalities in women
  • Fatty liver
  • Skin lesions
  • Growth abnormalities

Why does overweight lead to insulin resistance?
Some people store fat in the liver, muscle, and pancreas. This fat might block the signal that insulin sends to glucose transporters in cells, which is what makes the cells accept glucose from the bloodstream.

Excess weight also is thought to lead to chronic inflammation. Some research shows that this inflammation is what keeps insulin from working in insulin-resistant people.

How is insulin resistance diagnosed?
At-risk individuals will likely have their glucose level (either fasting glucose or glucose tolerance tests) and fasting insulin level measured. A person who has levels above the upper quartile usually is diagnosed as insulin resistant.

How is insulin resistance treated?
The first step is always lifestyle modification—weight loss, adoption of a carbohydrate-consistent diet consisting of mainly whole grains and little refined grains, and adoption of an exercise regimen.

Metformin, which prevents the liver from releasing glucose into the blood and increases the sensitivity of fat and muscle cells to insulin, is the most commonly prescribed medication.

 

References and recommended readings
Mathur R, Conrad Stöppler M. Insulin resistance. Available at: http://www.medicinenet.com/insulin_resistance/article.htm. Accessed June 8, 2012.

National Diabetes Information Clearinghouse (NDIC). Insulin resistance and prediabetes. Available at: http://diabetes.niddk.nih.gov/dm/pubs/insulinresistance/. Accessed June 8, 2012.