Alternate Names : Impaired Glucose Tolerance, Impaired Fasting Glucose, IGT, IFG
This is a condition where blood glucose levels are higher than normal but not yet high enough to be diagnosed as diabetes. This condition is a warning that a person is at high risk for developing type 2 diabetes. In fact, some studies have shown that most people who have pre-diabetes will develop type 2 diabetes within 10 years. Pre-diabetes is a serious health threat.
What is going on in the body?
Glucose is the main form of sugar found in the body and is a key source of energy for the body. In most people, an organ called the pancreas makes insulin to help control blood glucose levels in the body. But some people become resistant to the effects of insulin. As a result, glucose builds up in the body. Recent research shows that these higher-than-normal levels of glucose in the blood can cause long-term damage to the body. The heart is the most likely area for damage.
What are the causes and risks of the condition?
No one knows for sure what causes diabetes or pre-diabetes. Experts do agree that there are certain risk factors, especially for Type 2 diabetes and pre-diabetes. Obesity, lack of physical exercise, and age are three of the strongest risk factors. The following guidelines can be used to determine a person’s risk for developing pre-diabetes:
Anyone who is overweight and age 45 or older should be tested for pre-diabetes during the next visit to the doctor.
Those age 45 and older whose weight falls within healthy levels should ask their doctors about testing for pre-diabetes.
People who are overweight but younger than age 45 may need testing for pre-diabetes if other diabetes risk factors are present. Other risk factors include:
- family history of diabetes
- high blood pressure
- history of gestational diabetes or giving birth to a baby weighing 9 pounds or more
- low HDL cholesterol level with high triglycerides
- member of a high-risk ethnic group
People whose blood glucose levels are in the healthy range should be retested every 3 years. Those who test positive for pre-diabetes should then be tested for type 2 diabetes every 1 to 2 years.
Symptoms & Signs
People with pre-diabetes often don’t have symptoms. In fact, many people in the U.S. have diabetes and pre-diabetes without knowing. Symptoms, if there are any, develop so gradually that people often do not recognize them. An elevated blood glucose level is the only symptom of pre-diabetes.
Diagnosis & Tests
There are two different tests that doctors use to screen for pre-diabetes. Either one is acceptable.
- Fasting plasma glucose test, also called FPG. With this test, a person’s blood glucose level is measured following a fast, which means no food or drink has been taken in for at least 8 hours. If the blood glucose level is between 110 and 125 mg/dL, the person has pre-diabetes. Levels higher than that indicate type 2 diabetes.
- Oral glucose tolerance test, also called OGTT. With this test, a person’s blood glucose level is measured after a fast and 2 hours after drinking a special glucose drink. If the 2-hour blood glucose level is 140 to 199 mg/dL, the person has pre-diabetes. Levels at 200 mg/dL or higher indicate type 2 diabetes.
Prevention & Expectations
What can be done to prevent the condition?
A person at risk for pre-diabetes can delay, and possibly even prevent, the onset of illness simply by making the following changes:
- modest exercise
- losing weight, if overweight
In fact, a person can cut the risk for type 2 diabetes in half simply by walking 30 minutes a day and reducing his or her weight by about 5 to 10 percent. Healthy eating and exercise can provide huge benefits.
What are the long-term effects of the condition?
Most people who have pre-diabetes will develop type 2 diabetes within 10 years. Also, the person has 1.5 times the risk of heart disease. This includes high blood pressure, stroke, and heart attack.
What are the risks to others?
Diabetes and pre-diabetes are not catching, so there are no risks to others. However, there is a link between heredity and diabetes. So it is possible for a child to inherit the risk for diabetes from a parent.
Treatment & Monitoring
What are the treatments for the condition?
Modest lifestyle changes such as healthy eating, weight loss, and modest daily exercise are the main treatments for this condition. The following guidelines may help:
- Lose a modest amount of weight. Experts recommend that most people lose 5 to 10 percent of their total body weight. Even a loss of just 10 to 15 pounds can make a big difference.
- Increase the level of physical activity. Moderate exercise, such as walking, for 30 minutes a day at least 5 days a week can help lower blood glucose levels and can help with weight loss.
- Follow healthy eating habits. This will help lower heart disease risk factors and will make it easier to lose weight.
What are the side effects of the treatments?
There are no side effects from making the lifestyle changes that will help treat pre-diabetes.
What happens after treatment for the condition?
For some people who have pre-diabetes, making these changes can actually turn back the clock and return high blood glucose levels to a healthy range.
How is the condition monitored?
The FPG or OGTT test should be repeated at least every 1 to 2 years as long as a person still has pre-diabetes. If blood glucose levels fall back within the healthy range, then testing can be done every 3 years.
Revision date: July 8, 2011
Last revised: by Janet A. Staessen, MD, PhD