High-normal blood sugar raises your risk of full-blown type 2 diabetes by 50 percent within 10 years. It can double your risk of heart disease, nearly triple your risk of high blood pressure, and make you up to four times more likely to die from a heart attack. Insulin resistance, the metabolic glitch behind high-normal blood sugar, has also been associated with an increased risk of cancer.

The Rodney Dangerfield of Human Diseases
These dangers are often downplayed, if they’re mentioned at all. "I call prediabetes [another term for high-normal blood sugar] the Rodney Dangerfield of human diseases. It gets no respect," says John Buse, M.D., Ph.D., certified diabetes educator, associate professor of medicine at the University of North Carolina School of Medicine in Chapel Hill, and director of the university’s diabetes care center.

Genetics may account for up to 5 percent of diabetes and high-normal blood sugar risk. Currently, 64 percent of adult Americans are overweight, and 78 percent don’t get enough exercise, so it should come as no surprise that high-normal blood sugar is cutting a swath through the American population.

However, there’s a lot you can do on your own to protect your health if you have--or are at risk for--high-normal blood sugar. The key: Eat healthy and move more.

The Fat Connection
More than one-quarter of Americans have a body mass index (BMI) of 30 or more, a level considered obese. As a result, diabetes is on the rise and is becoming more common among younger people and even kids. (Among children, diabetes has steadily increased. For more information, see chapter 12.) The Centers for Disease Control and Prevention estimates that the number of people in their thirties with type 2 has increased by 70 percent.

As previously noted, research also suggests that belly fat--known as visceral fat, the kind that’s packed around internal organs and is often linked to high levels of the stress hormone cortisol--may be an even more potent risk factor than weight alone.

"Overweight, a high-fat diet, and visceral fat all intertwine to produce insulin resistance," says Dr. Buse. "We don’t completely understand the process yet, but one theory is that people who are insulin resistant are storing excess dietary fat in inappropriate places, such as in muscle cells and in the liver, which makes it harder for their body to use sugar as fuel."

Diabetes researchers have also discovered that body fat releases cytokines--chemical messengers that are supposed to help direct the immune system’s healing processes. But in excess quantities, cytokine signals can interfere with a cell’s ability to obey insulin. The result: Cells can’t absorb sugar.

Scientists suspect that during early diabetes, high insulin levels may raise heart disease risk into the danger zone by thickening artery walls and raising blood pressure. What’s more, insulin resistance is linked to the development of a very lethal kind of bad cholesterol--small, dense LDLs--that sets the stage for heart disease.