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Prediabetes exists when a person has glucose (blood sugar) levels higher than normal but not high enough to be diagnosed as diabetes. It often, but not always, escalates to type 2 diabetes, which accounts for an estimated 90 to 95 percent of cases of diabetes.

In the past, mildly elevated levels of glucose were often ignored. Today, glucose levels slightly above the normal range are a warning sign for an individual to take prompt action to prevent type 2 diabetes. In addition to being a strong risk factor for diabetes, prediabetes increases a person’s risk for heart disease and stroke, the U.S. Centers for Disease Control and Prevention (CDC) warns.

In the United States and worldwide, there has been a steady increase in the number of people diagnosed with diabetes. According to the CDC, the number of new cases of Americans diagnosed with diabetes increased by 54 percent between 1997 and 2004.

The CDC estimated in 2005 that, based on statistics from 1988 to 1994, 41 million Americans ages 40 to 74 had prediabetes – 40 percent of the total population in that age bracket. About 2 million American adolescents have prediabetes, according to a 2006 federal study using data from a 1999-2000 national survey. The CDC did not have more current statistics available as of early 2007, but with rates of obesity soaring in recent years, the number of people with prediabetes is now likely higher.

Given these facts, scientists are researching ways to identify people at risk for diabetes earlier. Unlike type 1 diabetes, it is believed that that with early identification, type 2 diabetes may be delayed or even prevented. A diagnosis of prediabetes has emerged as a condition for predicting individuals at risk for type 2 diabetes.

Prediabetes can be diagnosed by a physician using standard glucose tests. A fasting blood glucose test (FPG) or an oral glucose tolerance test (OGTT) can be used to identify the condition. These tests measure the level of glucose in the blood. If the level of glucose is found to be within a certain elevated range, prediabetes is diagnosed. The range, in milliliters per deciliter of blood, is 100 to 125 mg/dL for a fasting blood glucose test and 140 to 199 mg/dL for an oral glucose challenge test.

Even glucose at the high range of normal may be a concern. A recently completed 12-year Israeli study of more than 13,000 troops found that those with fasting glucose of 95 to 99 mg/dL were several times more likely than those with lower glucose to become diabetic.

Studies conducted by the U.S. Department of Health and Human Services indicate that individuals with prediabetes will likely develop type 2 diabetes within 10 years unless changes are made to their lifestyle. In addition, women diagnosed with prediabetes are at a high risk of developing gestational diabetes during pregnancy.

Treating prediabetes helps prevent the onset to type 2 diabetes and is important for other reasons as well. Research has shown that medical complications linked to diabetes may actually start in the prediabetes stage. The heart, blood vessels, kidneys and eyes may be damaged during the prediabetes stage. Treatment and prevention in the prediabetic state may slow down the damage of vital organs and body systems.

Recent research shows that:

• Almost 8 percent of the (prediabetic) participants in the Diabetes Prevention Program developed early-stage diabetic retinopathy.

• People with prediabetes are more likely to develop chronic kidney disease than those with normal glucose, mainly because of cardiovascular risk factors such as high blood pressure.
  
  
• Prediabetes increases the risk of heart disease, according to a nine-year study of more than 28,000 patients.
  
  
• The type of nerve damage associated with diabetes (diabetic neuropathy) can be present in people with prediabetes.
  
  
• Prediabetic women have increased risk of urinary incontinence, which can be improved with weight loss.

A condition related to prediabetes that also often develops before type 2 diabetes is insulin resistance, an impairment in the body’s ability to use insulin to process glucose for energy. In addition, people with prediabetes may have a cluster of cardiovascular risk factors known as metabolic syndrome.