Impaired glucose tolerance is a condition where blood glucose (sugar) levels are higher than normal, but not high enough to indicate diabetes. Also known as pre-diabetes, impaired glucose tolerance (IGT) affects about 20 million Americans, according to the Joslin Diabetes Center in Boston, Massachusetts. Impaired glucose tolerance is an important indicator of an increased risk of developing type 2 diabetes.
Impaired Glucose Tolerance Test
If you suspect you may have impaired glucose tolerance, your doctor may perform a glucose tolerance test in order to confirm this. Some of the available tests include:
- Fasting blood sugar test
- Glycated hemoglobin test
- Oral glucose tolerance test.
Even if your results are normal, your doctor may want you to perform another glucose tolerance test again in three years, especially if you are in a high-risk category. If your glucose tolerance results indicate abnormal glucose tolerance, your doctor will give you suggestions on how to make some healthy lifestyle changes. She may even prescribe medication to prevent the development of type 2 diabetes.
Metabolic Syndrome and Impaired Glucose Tolerance
Impaired glucose tolerance often presents as part of a number of conditions collectively known as metabolic syndrome, or Syndrome X. Metabolic syndrome conditions include:
- Dyslipidemia (abnormal levels of lipids in the blood)
- Hyperinsulinemia (high blood insulin levels)
- Hypertension (high blood pressure)
- Impaired glucose tolerance
- Insulin resistance
The presence of each of these conditions contributes individually to the development of diabetes.
What Is Insulin Resistance?
In some people, insulin levels may be normal or even high, but the body stops responding appropriately. Since the body needs insulin in order to help cells transport glucose for energy, insulin resistance leads to elevated blood sugar levels. The exact mechanism of insulin resistance is unknown. However, doctors and scientists have discovered that the condition is more common in overweight individuals and that a genetic predisposition exists.
Studies have shown that diet and exercise can help restore insulin sensitivity. Lowering the amount of fat and calories consumed and getting 30 minutes of aerobic exercise several times a week can reduce the risk of insulin resistance, as well as the development of type 2 diabetes.
Risk Factors for Abnormal Glucose Tolerance
As with many diseases, the risk of developing glucose intolerance and insulin resistance appears to involve both genetics and lifestyle.
The causes of impaired or abnormal glucose tolerance are similar to those of type 2 diabetes. Women are more likely to develop this condition than men, and a history of gestational diabetes further increases the risk of abnormal glucose tolerance results.
A family history of diabetes could indicate a genetic predisposition to problems involving glucose metabolism, and increase your risk of abnormal glucose tolerance. Certain ethnic groups are more likely to develop impaired glucose tolerance than others, including:
- African Americans
- Asian Americans
- Hispanic Americans
- Native Americans
- Pacific Islanders.
The occurrence of type 2 diabetes is also more common in these populations.
Other risk factors include:
- Inadequate sleep
- Lack of exercise
- Western lifestyle, including a low-fiber, high-fat diet.
Diet, Exercise and Impaired Glucose Tolerance
If a test shows abnormal glucose tolerance results, you may be able to control or even reverse impaired glucose tolerance by making healthy lifestyle changes, such as eating a healthy diet, as prescribed by your doctor, exercising regularly and maintaining a healthy weight.
American Diabetes Association. (n.d.) Genetics of diabetes. Retrieved March 20, 2010, from http://www.diabetes.org/diabetes-basics/genetics-of-diabetes.html.
International Diabetes Federation. (2009). Fact sheet impaired glucose tolerance (IGT). Retrieved March 25, 2010, from http://www.idf.org/node/1215?unode=52EAC7E3-76C3-4785-88D4-8B23E8219EF6.
Ip, M., Lam, K., Tsang, K., Lam, W. K.