A report by the Centers for Disease Control and Prevention, based on data from 2007, said the number represents an increase of about 3 million over two years. The CDC estimates another 57 million people have blood sugar abnormalities called pre-diabetes, which puts people at increased risk for the disease.
The percentage of people unaware that they have diabetes fell from 30 percent to 25 percent, according to the study.
Dr. Ann Albright, director of the CDC Division of Diabetes Translation, said the report has "both good news and bad news."
"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," Albright said in a statement.
"On the other hand, it is good to see that more people are aware that they have diabetes."
A message left Tuesday night seeking further comment from the CDC wasn't immediately returned.
The disease results from defects in insulin production that causes sugar to build up in the body. It is the seventh leading cause of death in the country and can cause serious health problems including heart disease, blindness, kidney failure and amputations.
Among adults, diabetes increased in both men and women and in all age groups, but still disproportionately affects the elderly. Almost 25 percent of the population 60 years and older had diabetes in 2007.
After adjusting for population age differences between various groups, the rate of diagnosed diabetes was highest among American Indians and Alaska Natives (16.5 percent). This was followed by blacks (11.8 percent) and Hispanics (10.4 percent), which includes rates for Puerto Ricans (12.6 percent), Mexican Americans (11.9 percent), and Cubans (8.2 percent).
By comparison, the rate for Asian Americans was 7.5 percent, with whites at 6.6 percent.