Diabetes is increasing everywhere, the study's lead author said. "It's a national problem."

The highest rate was in West Virginia, where about 13 in 1,000 adults were diagnosed with the disease. The lowest was in Minnesota, where the rate is 5 in 1,000.

About 90 percent of the cases are Type 2 diabetes, the form linked to obesity. The findings echo geographic trends seen with obesity and physical inactivity, which are also tied to heart disease. Southern states rank worst in those measures, too.

"It isn't surprising the problem is heaviest in the South -- no pun intended," said Matt Petersen, who oversees data and statistics for the American Diabetes Association.

But the study provides important new information on where new cases are emerging each year, giving a more timely picture of where the disease is exploding. The information should be a big help as the government and health insurers decide where to focus prevention campaigns, he said.

The study by the U.S. Centers for Disease Control and Prevention covered most states.
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More than 23 million Americans have diabetes. The number is growing quickly. About 1.6 million new cases were diagnosed in people 20 or older last year, according to the CDC.

Some studies have offered state-specific estimates of diabetes cases, but this is the first to chart where new cases are being diagnosed.

"It's important work," said Angela Liese, a diabetes researcher at the University of South Carolina, who was not involved in the CDC study.

The study involved a random-digit-dialed survey of more than 260,000 adults. Participants were asked if they'd ever been told by a doctor that they have diabetes, and when the diagnosis was made.

The annual rate of new diabetes cases rose from about 5 per 1,000 in the mid-1990s to 9 per 1,000 in the mid-2000s, according to data gathered for 33 states for which CDC had complete data for both time periods.

The researchers had data for 40 states for the years 2005-07. West Virginia, South Carolina, Alabama, Georgia, Texas and Tennessee had the highest rates, all at 11 per 1,000 or higher.

Minnesota, Hawaii and Wyoming had the lowest rates.

It's not completely clear why some states have a worse incidence than others. Older people, blacks and Hispanics tend to have higher rates of Type 2, and the South has large concentrations of older people and blacks. Texas has a large Hispanic population. However, West Virginia -- the state with the highest rate of new cases -- is overwhelmingly white.

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The report only asked about diagnosed diabetes. Because an estimated 1 in 4 diabetics have not been diagnosed, the findings probably underestimate the problem, Liese said.

The underestimates may be particularly bad in the rural South and other areas where patients have trouble getting health care, she noted.

Diabetes is increasing everywhere, said Karen Kirtland, the study's lead author, who said the rate rose in all states. "It's a national problem," she said