FRIDAY, May 26, 2006 (HealthDay News) -- The number of Americans diagnosed with type 2 diabetes has now topped 19 million, and a new study says a third of adults with the disease don't even know they have it.
The researchers found that another 26 percent of adults had "impaired fasting glucose," a precursor to diabetes.
"So, if you add that together with the 9.3 percent of people with diabetes, that means that fully one-third of the adult population -- 73 million Americans -- have diabetes or they may be on their way to getting it," said lead researcher Catherine Cowie, director of the diabetes epidemiology program at the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.
Her team's report appears in the June issue of Diabetes Care.
The researchers note that about 95 percent of all cases of diabetes in the United States fall under the category of type 2 disease -- a gradual loss of insulin production and sensitivity that's usually linked to overweight and obesity.
According to the U.S. National Institutes of Health and the U.S. Centers for Disease Control and Prevention, survey data from the National Health and Nutrition Examination Survey of 1988 to 1994 and 1999 to 2002 indicate the incidence of diabetes among people aged 20 and older has gone from about 5.1 percent of the population in the older survey to 6.5 percent by 2002.
"In the 1999 to 2002 survey, participants were interviewed to find out whether they had ever been told that they had diabetes," said Cowie. "In addition, the people had a blood test after they fasted overnight."
Among the 4,761 adults in surveyed, 9.3 percent had type 2 diabetes -- that translated to about 19.3 million people in the entire U.S. population, Cowie said. "In addition, we found that about one-third of the 9.3 percent don't know they have it," she noted.
Diabetes continues to affect blacks and Mexican-Americans about as much as whites, Cowie noted. "In fact, in blacks, diagnosed diabetes rose more significantly between the two surveys than it did for other groups," she said.
"In addition, it rose more significantly in men than in women," Cowie added.
It's even worse among older Americans. About 22 percent of those over 65 have diabetes, Cowie said. "Combine that with 40 percent of those with impaired fasting glucose, [and] it's affecting 62 percent of the adult population in that age group," she said.
There is a huge portion of the population who don't know they have diabetes or who are at risk for diabetes, Cowie said.
"We aren't doing a good enough job of diagnosing these one-in-three people who don't know they have diabetes as well as people who have pre-diabetes," Cowie said. "We really need to be a better job of convincing people that should be adopting healthy behaviors that will prevent these conditions."
One expert thinks that the number of undiagnosed diabetics and pre-diabetics may be underestimated.
"The findings suggest that the prevalence of undiagnosed diabetes is stable," said Dr. David L. Katz, an associate professor of public health and director of the Prevention Research Center at Yale University School of Medicine. "This might be true, and due to the fact that as diabetes rates are rising, we're at least attentive to it, and usually finding it when it's there. But this finding might also be misleading."
Undiagnosed diabetes may be less likely in people who participate in health surveys than those who do not, Katz said. "I am suspicious that there is more undiagnosed diabetes than these findings suggest," he noted.
"Since type 2 diabetes is often preventable, almost any is too much," Katz said. "Seeing a steady rise in the rates of this serious and potentially debilitating disease we have the wherewithal to prevent is compelling testimony of past failings and future needs," he said.
This is neither the first, nor the last time this message will be delivered in a scientific paper, Katz said.
"My hope is that we will do what needs to be done to make healthful diets and activity patterns more accessible to all, and diabetes a bit less so," he said.
For more on diabetes, head to the U.S. National Diabetes Clearinghouse.