Spurred by expanding waistlines and a lack of physical activity, America’s diabetes epidemic is particularly acute in Southeastern states like Georgia, a new study shows.

In the 644 counties in 15 mostly Southern states that make up what researchers are calling the “diabetes belt,” the rate of the disease was 11.7 percent, compared with 8.5 percent for the rest of the country, according to the Centers for Disease Control and Prevention study.

In 2009, 9.7 percent of Georgians had diagnosed diabetes -- up from 6.1 percent a decade ago, CDC data shows.

“Georgia has a big diabetes problem,” said Larry Phillips, an endocrinologist at Emory University.

People affected are often overweight and sedentary but also have a genetic tendency to develop diabetes, Phillips said. One reason for the Southeast’s high rates may be its higher proportion of African-Americans, who are more genetically prone to develop the disease for reasons scientists don’t fully understand, Phillips said.

Nationwide, diabetes affects an estimated 25.8 million people -- 8.3 percent of the population, CDC studies show. Diabetes is the seventh leading cause of death in the U.S. and a leading cause of kidney failure, nontraumatic lower-limb amputations, new cases of blindness, heart disease and stroke, according to the agency.

As many as one-third of Americans could have diabetes by 2050, the CDC estimates.

The “diabetes belt,” where the disease is more pervasive, includes Georgia, Alabama, Arkansas, Florida, South Carolina and Tennessee, among other states.

Other diabetes rates in the South include 11.7 percent in Alabama, 9.7 percent in Florida and 10.3 percent in both South Carolina and Tennessee.

Researchers long have known diabetes is more prevalent in the Southeast, said Lawrence Barker, one of the co-authors of the CDC study.

The new data, however, breaks the problem down to the county level -- allowing policymakers and other leaders to better identify the areas of greatest need where the most resources should be deployed, Barker said.

The highest in Georgia is Hancock County at 14 percent. In the metro Atlanta area, Henry County is tops with 10.8 percent, followed by DeKalb at 10.6 percent, Gwinnett and Fulton both at 9.5 percent, Cobb at 9.2 percent and Cherokee at 7.8 percent.

Not surprisingly, the areas where diabetes is widespread overlap with those where obesity rates are high, Barker said.

Obesity causes insulin resistance, which leads to diabetes, said Dr. Kimberly Redding, director of the health promotion and disease prevention programs at the state Department of Community Health.

The state is tackling the problem by finding ways to provide people with access to healthy foods, nutrition education and places to be physically active, Redding said. It also has given grants to community groups that have created farmers markets, community gardens and other healthy-eating programs, she said.

It’s a complex problem that takes a lot of resources to reverse, Redding said. “It’s not one that can be solved overnight.”

Groups such as the American Diabetes Association have campaigns to get people to be more active and eat right, but those habits haven't been adopted by society as a whole, said Dr. Harry Strothers, president of the Georgia Academy of Family Physicians.

“Cultural change is hard,” he said.