Prediabetes Symptoms and Diagnosis

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About 41 million Americans between the ages of 40 and 74 have "prediabetes." Prediabetes is a condition that can be considered an early, yet potentially reversible stage of the development of type 2 diabetes. Prediabetes is sometimes called impaired glucose tolerance or impaired fasting glucose (IGT/IFG), depending upon the test that yielded the abnormal result. In prediabetes, a person's blood sugar (glucose) levels are slightly higher than the normal range, but not high enough for a true diagnosis of diabetes. People with prediabetes have a significant risk of developing full-blown diabetes. In the Diabetes Prevention Program study, about 11% of people with prediabetes developed type II diabetes each year during the three year follow-up time of the study. Importantly, people with prediabetes generally have no symptoms of the condition.

Doctors generally use one of two different blood tests to diagnose diabetes and prediabetes. One is called the fasting plasma glucose test (FPG) in which a person's blood glucose level is measured first thing in the morning before breakfast. The normal fasting blood glucose level is below 100 mg/dl. A person with prediabetes has a fasting blood glucose level between 100 and 125 mg/dl. If the fasting blood glucose level is to 126 mg/dl or above, a person is considered to have diabetes.

The second test used in the diagnosis of diabetes is the oral glucose tolerance test (OGTT), although this test is no longer commonly used as in the past. This test may be used to diagnose gestational diabetes in pregnant women. In this test, a person's blood glucose is measured in the morning after fasting overnight and again two hours after drinking a glucose-rich beverage. The normal value for blood glucose is below 140 mg/dl two hours after the drink. In prediabetes, the two-hour blood glucose is 140 to 199 mg/dl. If the two-hour blood glucose rises to 200 mg/dl or above, a person has diabetes.