JoAnne Zoller Wag- ner's diagnosis as prediabetic wasn't enough to compel her to change her habits and lose 30 pounds. Not even with the knowledge her sister had died because of diabetes.

"I didn't have that sense of urgency," said the Pasadena, Md., woman.

But nine months later, doctors told Wagner her condition had worsened. She had type 2 diabetes.

That scared her into action. Two years later, the 55-year-old has slimmed down. She exercises regularly and her blood sugar levels are back in the healthy range. Thanks to her success, she was able to avoid diabetes medication.

Diabetics who manage to turn things around, getting their blood sugar under control — either escaping the need for drugs or improving enough to quit them — are drawing interest from the medical community.

This summer an American Diabetes Association task force will focus on this group of patients and whether they can be considered "cured."

"For right now, we're not saying they're cured, but the bottom line is ... good glucose control, less infections," said Sue McLaughlin, president of healthcare and education for the American Diabetes Association.

Being overweight is the leading risk for type 2 diabetes. Genetics also plays a role, and blacks, Hispanics and American Indians are at greater risk than whites.

Nearly 57 million Americans are prediabetic. Another 18 million have been diagnosed with diabetes, while the diabetes association estimates almost 6 million more Americans have diabetes and don't know it. Some 90 percent to 95 percent of diabetics have type 2, linked to obesity.

The future is potentially even gloomier, with one study estimating that one of every three children born in the U.S. in 2000 will eventually develop diabetes.

But the news isn't all bad. Thirty minutes of daily exercise and a 5 percent to 10 percent loss in body weight can lower the odds of diabetes by nearly 60 percent and is more effective than medicine in delaying its onset, according to a diabetes prevention study.

Even diabetics who have resorted to weight loss surgery have seen their blood sugar levels return to normal.

Whatever the route, weight loss is key, doctors say.

"There is no special diet. You've got to eat fewer calories than your body burns," said Dr. Robert Rizza, a Mayo Clinic endocrinologist .

Many stop short of calling successful patients cured.

Dr. Philipp Scherer, director of the diabetes research center at University of Texas Southwestern, describes diabetes as a one-way road. He said it can be stopped in its tracks with diet and exercise, but there's no turning back.

Dr. Kevin Niswender, an assistant professor in the department of medicine at Vanderbilt Medical Center, said "you could call somebody cured," but that patient still needs to be followed closely.

Doctors caution that, for some diabetics, lowering blood sugar may be only temporary. Stress, weight gain and other factors can push it back to unhealthy levels.

"Blood sugars can come down to normal. Then the issue is how long does that last?" said Dr. Sue Kirkman, vice president of clinical affairs for the diabetes association.

In other cases, patients are diagnosed so late that blood sugar can't be brought back to normal, even with weight loss, she said. As the disease progresses, even those who made diet and lifestyle changes might eventually have to go on medications.