Prevalence of diabetes and high risk for diabetes using A1C criteria in the US population in 1988-2006
Author(s)
Type
Journal Article
Abstract
OBJECTIVE We examined prevalences of previously diagnosed diabetes and undiagnosed diabetes and high risk for diabetes using recently suggested A1C criteria in the U.S. during 2003–2006. We compared these prevalences to those in earlier surveys and those using glucose criteria.
RESEARCH DESIGN AND METHODS In 2003–2006, the National Health and Nutrition Examination Survey included a probability sample of 14,611 individuals aged ≥12 years. Participants were classified on glycemic status by interview for diagnosed diabetes and by A1C, fasting, and 2-h glucose challenge values measured in subsamples.
RESULTS Using A1C criteria, the crude prevalence of total diabetes in adults aged ≥20 years was 9.6% (20.4 million), of which 19.0% was undiagnosed (7.8% diagnosed, 1.8% undiagnosed using A1C ≥6.5%). Another 3.5% of adults (7.4 million) were at high risk for diabetes (A1C 6.0 to <6.5%). Prevalences were disproportionately high in the elderly. Age-/sex-standardized prevalence was more than two times higher in non-Hispanic blacks and Mexican Americans versus non-Hispanic whites for diagnosed, undiagnosed, and total diabetes (P < 0.003); standardized prevalence at high risk for diabetes was more than two times higher in non-Hispanic blacks versus non-Hispanic whites and Mexican Americans (P < 0.00001). Since 1988–1994, diagnosed diabetes generally increased, while the percent of diabetes that was undiagnosed and the percent at high risk of diabetes generally decreased. Using A1C criteria, prevalences of undiagnosed diabetes and high risk of diabetes were one-third that and one-tenth that, respectively, using glucose criteria.
CONCLUSIONS Although A1C detects much lower prevalences than glucose criteria, hyperglycemic conditions remain high in the U.S., and elderly and minority groups are disproportionately affected.
The A1C test has recently been recommended for diagnosing diabetes, based on a detailed analysis of its attributes by an international expert committee (1). Laboratory-measured A1C is now as accurate and precise as glucose assays due to improvements in instrumentation and standardization. A1C samples can be obtained at any time, require no patient preparation, and are relatively stable at room temperature after collection. A1C has substantially less biologic variability and is unaffected by acute effects of stress or illness. As a measure of long-term glycemic exposure, A1C has been shown to be better and more consistently correlated with retinopathy in the setting of observational studies and clinical trials in type 1 and type 2 diabetic patients, which have established widely accepted A1C treatment goals for diabetes. A cut point of ≥6.5% for the diagnosis of diabetes was recommended by the committee as optimal for detecting a level of retinopathy thought to be diabetes specific and not due to other conditions (e.g., hypertension). A limitation of A1C for diagnosis is that the committee could not define a specific intermediate threshold at which increased risk for diabetes clearly begins. While there is a continuum of risk even at values into the normal range, the committee suggested the range of ≥6.0 to <6.5% to represent the highest risk for progression to diabetes and one at which preventive measures might be implemented, with additional consideration of prevention efforts at lower levels in the presence of other risk factors. The committee hoped that its report would serve as a stimulus to the scientific community and professional organizations for considering the A1C assay for diagnosis of diabetes.
A change in diagnostic criteria has important public health implications pertaining to the magnitude of the population with diabetes or at high risk of diabetes. This report examines the prevalence of diagnosed and undiagnosed diabetes and high risk of diabetes based on self-report and A1C criteria in the U.S. population during 2003–2006. Prevalences are compared with those using the A1C criteria in 1988–1994 and 1999–2002. Finally, we compare the concordance in prevalence of undiagnosed diabetes using the new A1C criteria to criteria based on fasting plasma glucose and 2-h plasma glucose from an oral glucose tolerance test (OGTT).
RESEARCH DESIGN AND METHODS In 2003–2006, the National Health and Nutrition Examination Survey included a probability sample of 14,611 individuals aged ≥12 years. Participants were classified on glycemic status by interview for diagnosed diabetes and by A1C, fasting, and 2-h glucose challenge values measured in subsamples.
RESULTS Using A1C criteria, the crude prevalence of total diabetes in adults aged ≥20 years was 9.6% (20.4 million), of which 19.0% was undiagnosed (7.8% diagnosed, 1.8% undiagnosed using A1C ≥6.5%). Another 3.5% of adults (7.4 million) were at high risk for diabetes (A1C 6.0 to <6.5%). Prevalences were disproportionately high in the elderly. Age-/sex-standardized prevalence was more than two times higher in non-Hispanic blacks and Mexican Americans versus non-Hispanic whites for diagnosed, undiagnosed, and total diabetes (P < 0.003); standardized prevalence at high risk for diabetes was more than two times higher in non-Hispanic blacks versus non-Hispanic whites and Mexican Americans (P < 0.00001). Since 1988–1994, diagnosed diabetes generally increased, while the percent of diabetes that was undiagnosed and the percent at high risk of diabetes generally decreased. Using A1C criteria, prevalences of undiagnosed diabetes and high risk of diabetes were one-third that and one-tenth that, respectively, using glucose criteria.
CONCLUSIONS Although A1C detects much lower prevalences than glucose criteria, hyperglycemic conditions remain high in the U.S., and elderly and minority groups are disproportionately affected.
The A1C test has recently been recommended for diagnosing diabetes, based on a detailed analysis of its attributes by an international expert committee (1). Laboratory-measured A1C is now as accurate and precise as glucose assays due to improvements in instrumentation and standardization. A1C samples can be obtained at any time, require no patient preparation, and are relatively stable at room temperature after collection. A1C has substantially less biologic variability and is unaffected by acute effects of stress or illness. As a measure of long-term glycemic exposure, A1C has been shown to be better and more consistently correlated with retinopathy in the setting of observational studies and clinical trials in type 1 and type 2 diabetic patients, which have established widely accepted A1C treatment goals for diabetes. A cut point of ≥6.5% for the diagnosis of diabetes was recommended by the committee as optimal for detecting a level of retinopathy thought to be diabetes specific and not due to other conditions (e.g., hypertension). A limitation of A1C for diagnosis is that the committee could not define a specific intermediate threshold at which increased risk for diabetes clearly begins. While there is a continuum of risk even at values into the normal range, the committee suggested the range of ≥6.0 to <6.5% to represent the highest risk for progression to diabetes and one at which preventive measures might be implemented, with additional consideration of prevention efforts at lower levels in the presence of other risk factors. The committee hoped that its report would serve as a stimulus to the scientific community and professional organizations for considering the A1C assay for diagnosis of diabetes.
A change in diagnostic criteria has important public health implications pertaining to the magnitude of the population with diabetes or at high risk of diabetes. This report examines the prevalence of diagnosed and undiagnosed diabetes and high risk of diabetes based on self-report and A1C criteria in the U.S. population during 2003–2006. Prevalences are compared with those using the A1C criteria in 1988–1994 and 1999–2002. Finally, we compare the concordance in prevalence of undiagnosed diabetes using the new A1C criteria to criteria based on fasting plasma glucose and 2-h plasma glucose from an oral glucose tolerance test (OGTT).
Date Issued
2010-03-01
Date Acceptance
2009-12-10
Citation
Diabetes Care, 2010, 33 (3), pp.562-568
ISSN
0149-5992
Publisher
American Diabetes Association
Start Page
562
End Page
568
Journal / Book Title
Diabetes Care
Volume
33
Issue
3
Copyright Statement
© 2010 by the American Diabetes Association. Readers may use this article as long as the work is properly
cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.
org/licenses/by-nc-nd/3.0/ for details.
cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.
org/licenses/by-nc-nd/3.0/ for details.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000275562700021&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Life Sciences & Biomedicine
Endocrinology & Metabolism
Publication Status
Published
Date Publish Online
2010-03-01