It's the gray area between normal blood sugar levels and those that indicate diabetes. Though it typically doesn't cause symptoms, up to 70 percent of people with prediabetes develop the full-blown disease. Even if they don't, they face a higher risk of heart attack, stroke, and possibly cognitive decline and certain cancers. While experts agree that repeated fasting glucose levels over 125 milligrams per deciliter indicate diabetes, they disagree on when prediabetes starts. Most set it at 100 mg/dL, but some stick by an older cutoff of 110 mg/dL.

Our take

The broader guidelines are reasonable, but keep in mind that blood sugar levels represent a continuum, and any cutoff point is somewhat arbitrary. In general, the higher your blood glucose level the greater your risk, but the presence of other risk factors such as obesity, high blood pressure, and elevated LDL (bad) cholesterol are reasons to take even slightly elevated blood sugar seriously.

Does prediabetes require drugs?

That's uncertain. But it is clear that lifestyle measures should be tried first. A 2006 review of seven major prevention trials concluded that while medication reduced the progression to type 2 diabetes, losing excess weight, becoming physically active, and consuming a healthy diet were more effective.

Our take

Prediabetics should have their blood sugar checked at least annually. If lifestyle changes fail to normalize blood glucose, discuss the risks and benefits of drug therapy with your physician, especially if you have heart disease or coronary risk factors. You should also consider drugs to control high blood pressure or cholesterol levels, and talk with your doctor about low-dose aspirin to lower your risk of heart attack.

Type 2 diabetes by the numbers: A growing crisis