What is insulin resistance? Insulin resistance is a condition where the body becomes resistant to insulin, particularly the way it functions to keep blood sugar levels within normal range. Insulin resistance often appears along with or as a component of other metabolic problems, such as diabetes, high blood pressure, high cholesterol, heart disease, and polycystic ovarian syndrome. It often develops long before any of these diseases appear.
What is insulin? Insulin is a hormone that helps remove sugar or glucose from the bloodstream and move it into cells to be used for energy. When food is broken down into glucose by the digestive system, the pancreas releases insulin to help transport glucose into fat and muscle cells to be used for energy.
Why do blood sugar levels rise? Insulin resistance happens when insulin is no longer effective at transporting glucose into cells. Glucose builds up in the bloodstream and causes blood sugar levels to rise. The pancreas then produces more insulin in an effort to reduce glucose, but most of it is ineffective. So the patient may have both high blood sugar and high insulin levels.
Insulin Resistance Causes
The exact cause of insulin resistance is not known. However, researchers have identified genes that may increase the likelihood of developing insulin resistance and type 2 diabetes. Ethnicity, lifestyle, and certain medications may also play a part in development.
Insulin Resistance Risk Factors
- History of type 2 diabetes
- Parent or sibling with diabetes
- History of gestational diabetes
- Polycystic ovarian syndrome
- Obesity (especially abdominal obesity) with a BMI of 30 or more
- Waist-to-hip ratio or waist circumference in the high-risk range
- Above-normal fasting glucose or glucose tolerance test results
Type 2 Diabetes and Metabolic Syndrome
Insulin resistance causes blood sugar levels to rise and increases the risk for developing prediabetes or type 2 diabetes. When a patient has insulin resistance and three or more of the problems listed below, they are considered to have metabolic syndrome (formerly called syndrome X). Metabolic syndrome is the name given to the combination of risk factors that increases risk for cardiovascular disease and diabetes.
- Waist circumference of 40 inches or more for men and 35 inches or more for women
- Triglyceride level 150 mg/dL or higher
- HDL or "good" cholesterol less than 40 mg/dL for men and less than 50 mg/dL for women
- Blood pressure of 130/85 or higher
- Fasting glucose or blood sugar of 100 mg/dL or higher (or taking diabetes medication)
Insulin Resistance Symptoms
There are usually no symptoms. However, severe insulin resistance can cause acanthosis nigricans, which is seen as velvety dark patches of skin, usually around folds, such as the neck, armpits, elbows, knees, knuckles, and groin area. If blood sugar levels are high, the symptoms may be similar to those for type 2 diabetes.
Insulin Resistance Diagnosis and Tests
Currently, there is not a commonly used insulin resistance test. Insulin levels can be measured, but the test is expensive and complicated and most often used for research.
Doctors can test for prediabetes or type 2 diabetes with the following tests:
Insulin Resistance Treatment
There are no FDA-approved medications for insulin resistance or for preventing diabetes or pre-diabetes. The American Diabetes Association recommends the drug metformin for people who are at very high risk or who have had impaired results for both the fasting glucose and glucose tolerance tests. Insulin resistance and pre-diabetes may be reversed or avoided with lifestyle changes, and these are usually tried first.
- Moderate physical activity, at least 30 minutes a day, 5 to 7 days per week. Physical activity makes muscle cells more sensitive to insulin.
- A 5 to 7% weight loss can prevent or delay diabetes by almost 60%. Studies have shown people over the age of 60 could lower their risks by 70% with same amount of weight loss.
- Eating natural foods high in fiber helps to decrease risk.
Sources:
DeFronzo, R A; Ferrannini, E. "Insulin Resistance. A Multifaceted Syndrome Responsible for NIDDM, Obesity, Hypertension, Dyslipidemia, and Atherosclerotic Cardiovascular Disease." Diabetes Care March 1991 14(3):173-194 http://care.diabetesjournals.org/content/14/3/173.short
Kahn, Barbara B; Flier, Jeffrey S. "Obesity and Insulin Resistance." J Clin Invest Aug 2000 106(4)473-481
Insulin Resistance and Diabetes. National Diabetes Information Clearinghouse. Accessed May 4, 2011. http://diabetes.niddk.nih.gov/dm/pubs/insulinresistance/
Metabolic Syndrome. American Heart Association. Accessed May 10, 2011. http://www.americanheart.org/presenter.jhtml?identifier=4756
Rao, Goutham MD. "Insulin Resistance Syndrome." Am Fam Physician Mar 2001 15;63(6):1159-1164
