Diabetes Dateline
Spring/Summer 2009
New Survey Results Show Huge Burden of Diabetes
Study Includes Sensitive Test of Blood Glucose Abnormalities
Nearly 13 percent of U.S. adults age 20 and older have diabetes, but 40 percent of them have not been diagnosed, according to a study by epidemiologists from the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC).
A Diabetes Epidemic
“We’re facing a diabetes epidemic that shows no signs of abating, judging from the number of individuals with pre-diabetes,” said Catherine Cowie, Ph.D., lead author of the study and director of the National Institute of Diabetes and Digestive and Kidney Diseases’ (NIDDK’s) Diabetes Epidemiology Program. Pre-diabetes is a condition marked by elevated blood glucose, also called blood sugar, that is not yet in the diabetic range.
The study is based on 2005–2006 National Health and Nutrition Examination Survey (NHANES) data collected by the CDC’s National Center for Health Statistics. Data included readings from the fasting blood glucose (FBG) test and the oral glucose tolerance test (OGTT). Whereas the FBG test is a measure of blood glucose after an overnight fast, the OGTT is a measure of blood glucose 2 hours after a person drinks a premeasured sugary beverage.
The OGTT gives more information about blood glucose abnormalities than the FBG test. The FBG test is easier to administer and less costly
than the OGTT, but the 2-hour test is more sensitive in identifying diabetes and pre-diabetes, especially in older people. Thus the FBG is generally used for diagnosis in clinical practice, but the OGTT is preferred for research.
Greater Confidence
“For years, diabetes prevalence estimates have been based mainly on data that included a fasting glucose test but not an OGTT,” said Cowie. The 2005–2006 NHANES is the first national survey in 15 years to include the OGTT. “The addition of the OGTT gives us greater confidence that we’re seeing the true burden of diabetes and pre-diabetes in a representative sample of the U.S. population.”
Diabetes is a group of diseases marked by high levels of blood glucose resulting from defects in insulin production, insulin action, or both. Diabetes is the most common cause of blindness, kidney failure, and amputations in adults and a leading cause of heart disease and stroke. Type 2 diabetes accounts for up to 95 percent of all diabetes cases and virtually all cases of undiagnosed diabetes. Pre-diabetes, which causes no symptoms, substantially raises the risk of heart attack or stroke and of developing type 2 diabetes.
U.S. Diabetes and Pre-diabetes Statistics: 2005–2006 Versus 1988–1994
Researchers from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the Centers for Disease Control and Prevention analyzed data from two National Health and Nutrition Examination Surveys, one for 2005–2006 and the other for 1988–1994, and found the following:
- Nearly one-third of people ages 65 and older have diabetes; an additional 40 percent have pre-diabetes.
- The rate of diagnosed diabetes increased between the surveys, but the rate of undiagnosed diabetes remained relatively stable.
- The overwhelming majority of people with pre-diabetes have not been diagnosed, and this finding is unchanged despite research showing that weight loss through lifestyle changes can delay progression to diabetes in people identified with pre-diabetes.
- Minority groups continue to bear a disproportionate burden. The prevalence of diabetes, both diagnosed and undiagnosed, in non-Hispanic blacks and Mexican Americans is about 70 to 80 percent higher than that of non-Hispanic whites.
- Diabetes prevalence was virtually the same in men and women, as was the proportion of undiagnosed cases.
- Pre-diabetes is more common in men than in women—36 percent compared with 23 percent.
- Diabetes rates are low in youths between the ages of 12 and 19, but about 16 percent have pre-diabetes.
“These findings have grave implications for our health care system, which is already struggling to provide care for millions of diabetes patients, many of whom belong to vulnerable groups, such as the elderly or minorities,” said NIDDK Director Griffin P. Rodgers, M.D., M.A.C.P. “Of paramount importance is the need to curb the obesity epidemic, which is the main factor driving the rise in type 2 diabetes.”
National Sample
The survey included 7,267 people, who represented a national sample of participants ages 12 and older. Participants were interviewed in their homes and received a physical exam. FBG and OGTT readings were taken. The findings were then compared with those of the last NHANES survey that included the OGTT, which was conducted from 1988 to 1994. The researchers reported their findings in the February 2009 issue of Diabetes Care.
For more information about diabetes, including health information for the public, visit www.diabetes.niddk.nih.gov.
NIH Publication No. 09–4562
August 2009
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