WEDNESDAY, Jan. 28 (HealthDay News) -- The most recent analysis of data on diabetes in the United States finds that almost 13 percent of adults aged 20 and older have the condition, 40 percent of whom have not been diagnosed.
That's a larger proportion of diagnosed patients than noted in a previous study, although the percentage of undiagnosed individuals has remained the same.
"We can say for certain that diagnosed diabetes has increased significantly between the two surveys, from 5.1 percent [in 1988-1994] to 7.7 percent [in 2005-2006]. It seems it has particularly increased in blacks," said Catherine C. Cowie, director of the Diabetes Epidemiology Program at the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.
"On the other hand, the prevalence of undiagnosed diabetes and pre-diabetes [around 30 percent of the population] is generally stable, and that's really good news," she said. "If undiagnosed diabetes has stayed pretty much the same and diagnosed diabetes has gone up, then we're doing a better job of detecting diabetes."
Cowie is lead author of a study published in the February issue of Diabetes Care.
The wide prevalence of pre-diabetic conditions is still troubling, experts said. Pre-diabetes is a condition in which blood glucose levels are higher than normal but not high enough to be classified as diabetes. Pre-diabetic people are at increased risk for developing type 2 diabetes, heart disease and stroke.
"There is a large population that has pre-diabetes. Also, one-third are not diagnosed for diabetes and pre-diabetes, so this is a huge population issue that we'll have to deal with as time goes on," warned Dr. Spyros Mezitis, an endocrinologist with Lenox Hill and NewYork-Presbyterian hospitals and professor of medicine at Weill Medical College of Cornell University, New York City.
"We're not working on preventing as much as we should. We have a problem with 20 million Americans having diabetes, but the projections are that this will [dramatically increase]," he said. "We're not talking about curing the disease in the next few years. It's all going to be about management."
Diabetes carries with it a number of serious complications, including kidney failure, blindness, amputation and even death.
The national survey on which this study was based involved almost 7,300 people aged 12 and over who were interviewed in their homes in 2005 and 2006. Participants also had blood glucose measurements taken. This data was compared to earlier data gathered from 1988-1994.
The survey included data on an oral glucose tolerance test (OGTT) which had not been used for 15 years, in addition to other measures of blood sugar. The OGTT is a more sensitive test.
Overall, more than 40 percent of the people surveyed had either diabetes or pre-diabetes. This included one-third of the elderly with diabetes and three-quarters with pre-diabetes.
Mexican Americans and non-Hispanic blacks had about twice the rate of diabetes as non-Hispanic whites, although undiagnosed diabetes in these populations was not higher.
"In the Mexican-American population, doctors are becoming more and more aware that this is a big problem that was, in the past, underdiagnosed and is now diagnosed more readily," said Dr. Stuart Weiss, clinical assistant professor of medicine at New York University School of Medicine in New York City. "We're not letting that slide as much as we used to."
Pre-diabetes is more common in men (36 percent) than in women (23 percent). About 16 percent of youths aged 12 to 19 have pre-diabetes, although diabetes itself is rare.
There have been decreases in the proportion of undiagnosed diabetes only among obese people.
"This study emphasizes that it's all about lifestyle, and it's all about how people eat and amount of calories that they burn and trying to keep that together," Weiss said. "Everybody's eating and not exercising enough."
There's more on this condition at the U.S. National Diabetes Education Program.
SOURCES: Catherine C. Cowie, Ph.D., director, Diabetes Epidemiology Program, U.S. National Institute of Diabetes and Digestive and Kidney Diseases; Spyros Mezitis, M.D., Ph.D., endocrinologist, Lenox Hill Hospital and New York Presbyterian Hospital, professor of medicine, Weill Medical College of Cornell University, New York City; Stuart Weiss, M.D., clinical assistant professor of medicine, New York University School of Medicine, New York City; February 2009, Diabetes Care