Some 24 million Americans suffer from diabetes, an increase of more than three million in just the last two years, according to US government figures.
Data released last week by the US Centers for Disease Control and Prevention (CDC) showed that nearly eight percent of the US population have the dreaded disease, associated with high levels of blood glucose, which can lead to heart disease, blindness, kidney failure and amputations.
About 57 million people are estimated to have "pre-diabetes," and face an increased risk for the disease.
The CDC said that among diabetics, the number of respondents who did not know they had the disease declined from 30 percent to 25 percent compared to 2005, the CDC said.
"These new estimates have both good news and bad news," said Ann Albright, director of the division of the CDC which compiles data on diabetes.
"It is concerning to know that we have more people developing diabetes," she said.
"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."
Diabetes is the seventh leading cause of death in the United States, claiming more than 200,000 lives a year.
Although diabetes increased for all adults of both genders, the elderly were hit hardest. One-quarter of Americans 60 years and older had diabetes in 2007.
Rates of diagnosed diabetes were highest among Native Americans (16.5 percent), followed by African Americans (11.8 percent) and Hispanics (10.4 percent).
For Asian Americans, the diabetes rate was 7.5 percent, while for whites it was 6.6 percent.
The findings update diabetes prevalence estimates reported two years ago, which were published in 2007.