MONDAY, Oct. 26, 2015 (HealthDay News) -- Doctors should screen overweight and obese adults between 40 and 70 years old for abnormal blood sugar levels and type 2 diabetes, according to new recommendations from the U.S. Preventive Services Task Force.

People with elevated blood sugar (glucose) levels should then be referred to intensive behavioral counseling that emphasizes healthy eating and regular exercise, the guidelines say.

"People with abnormal blood glucose have a higher risk for progression to [type 2] diabetes. By finding abnormal blood glucose early, you may prevent that pathway by starting lifestyle interventions early," said Dr. Michael Pignone, a task force member and professor of medicine at the University of North Carolina at Chapel Hill.

As many as 86 million American adults have abnormal blood sugar levels. Without lifestyle changes, between 15 and 30 percent of them will develop type 2 diabetes within five years, according to background information in the guidelines.

Diabetes, which is increasingly prevalent in the United States, is a leading cause of heart attack and stroke, Pignone said.

Being overweight or obese is a significant risk factor for type 2 diabetes, Pignone said. What constitutes overweight? For a woman 5 feet 6 inches tall, overweight begins at about 155 pounds. Obesity for that same woman starts at 186 pounds, according to the U.S. National Heart, Lung, and Blood Institute. For a man 6 feet tall, overweight begins at 184 pounds, and obesity at 221.

Other modifiable risk factors include having a high percentage of abdominal fat, being physically inactive and smoking, the guidelines said.

Currently, the American Diabetes Association recommends routine screening in adults 45 years or older, and earlier screening in people with multiple risk factors for type 2 diabetes. A number of other health groups recommend screening for type 2 diabetes only in people who have risk factors, the new guidelines said.

The new recommendations were published in the Oct. 27 issue of the Annals of Internal Medicine.

The task force, an independent panel of experts in primary care and prevention, last issued guidelines on screening for blood sugar in 2008. The new review found six studies suggesting lifestyle-modification programs can help prevent type 2 diabetes, Pignone said. The research concerned people younger than 70, which is why the guidelines stop at that age, he added.