New diabetes cases in the U.S. have leveled off after years of sharp increases in a surprising sign that health officials may be starting to get America’s obesity epidemic under control.

Diabetes was diagnosed in 8.3 percent of Americans in 2012 compared with 7.9 percent in 2008, according to a study released today in the Journal of the American Medical Association. The caseload had jumped dramatically from 1990 when just 3.5 percent of the U.S. population were newly diagnosed with diabetes.

The finding fits with previous research that has showed the obesity epidemic in the U.S. is stabilizing as celebrities, governments and corporations have pushed to improve Americans’ diets and exercise. Obesity is a main cause of Type 2 diabetes, which usually develops in adults and is the most common form of the disease. Still, the news surprised researchers.

“I wasn’t expecting something like this at all,” Betul Hatipoglu, an endocrinologist at Cleveland Clinic, said. “We have been continuing to get signals that diabetes was continuing to be on the rise and becoming an even bigger problem. This study gives us hope it might have plateaued at some point.”

The U.S. Centers for Disease Control and Prevention in 2010 estimated that 1 in 3 adult Americans would have diabetes by 2050 as the population ages and there are more minorities at high risk for the disease. The slowdown in new cases may mean the epidemic can be avoided, said Ann Albright, director of the CDC’s division of diabetes translation.

‘Runaway Train’

“That gives us hope that we are beginning to slow down this runaway train,” said Albright, an author of today’s study from the CDC. “You’ve got to slow that roaring train down before we can begin to reverse and see declines.”

More than 29 million people in the U.S. have diabetes, according to the latest data from the CDC. Diabetics can’t produce insulin to convert food into energy or their bodies don’t use insulin properly.

While most groups saw a leveling off of cases, the disease continues to increase among Hispanics, blacks and those with less than a high school education. Hatipoglu said resources for prevention and education should be more focused on those groups rather than a broad message to the general population.

In her medical practice, Hatipoglu said she has seen a benefit from educational campaigns, particularly in schools where children pass along information they learn about diet and exercise to their parents.

The study looked at the health of 665,000 adults ages 20 to 79 based on surveys they provided the U.S. Census Bureau.