TUESDAY, June 24 (HealthDay News) -- Almost 24 million Americans had diabetes in 2007, an increase of more than 3 million over two years, the U.S. Centers for Disease Control and Prevention reported Tuesday.

In addition, another 57 million Americans had pre-diabetes, which puts people at increased risk for diabetes.

There was some good news. Over two years, the proportion of people with diabetes who don't know they have the disease decreased from 30 percent to 25 percent.

"It is concerning to know that we have more people developing diabetes, and these data are a reminder of the importance of increasing awareness of this condition, especially among people who are at high risk," Dr. Ann Albright, director of the CDC Division of Diabetes Translation, said in a prepared statement.

"On the other hand, it is good to see that more people are aware that they have diabetes. That is an indication that our efforts to increase awareness are working, and more importantly, that more people are better prepared to manage this disease and its complications," Albright said.

Among adults, diabetes increased in both men and women in all age groups, but the disease still disproportionately affects the elderly. Almost 25 percent of people aged 60 and older had diabetes in 2007, the CDC said.

Ethnic and minority disparities persist in rates of diagnosed diabetes: Native Americans and Alaska Natives, 16.5 percent; blacks, 11.8 percent; Hispanics, 10.4 percent; Asian Americans, 7.5 percent; and whites, 6.6 percent.

The data is in the 2007 Diabetes Fact Sheet developed by the CDC and other federal agencies.

The CDC also released estimates of diagnosed diabetes for all counties in the United States, which show higher rates of diabetes in areas of the Southeast and Appalachia where people traditionally been recognized as being at higher risk for heart disease, stroke and other chronic diseases.

"These data are an important step in identifying the places in a state that have the greatest number of people affected by diabetes. If states know which communities or areas have more people with diabetes, they can use that information to target their efforts or tailor them to meet the needs of specific communities," Albright said.

Diabetes, the seventh leading cause of death in the United States, can cause serious health complications such as heart disease, blindness, kidney failure and lower extremity amputations.

More information

The CDC has more about diabetes.