Reports of possible inappropriate use of some A1c point-of-care (POC) tests have come to light recently. According to a December 2010 Washington Post article, the tests have been used for screening individuals for diabetes in various settings such as health fairs, drug stores, and "wellness days" sponsored by corporations. A1c POC tests have not been recommended for screening or diagnosing diabetes, and the issue raises concerns that some people may be given misleading health information.
Point-of-care tests are a quick and easy means of detecting or measuring a particular substance in blood or other sample. Generally, they are performed outside of a laboratory setting and are designed to be simple to use. The technology employed is often relatively uncomplicated so that the tests don't require extensive training for proper use. POC tests that measure A1c levels help diabetics determine how well they have controlled their blood glucose levels over the past few months.
Until lately, A1c tests were recommended only for monitoring purposes. They were to be used only after a diagnosis of diabetes was established using fasting glucose and/or glucose tolerance tests. However, improvements in technology have led to more accurate laboratory-based A1c assays. Last year, the American Diabetes Association (ADA) noted that newer versions of laboratory tests that have been standardized through the National Glycohemoglobin Standardization Program have been proven to have sufficient accuracy and reproducibility to be reliable in screening and diagnosing diabetes.
In light of this, the ADA recommended that A1c tests be included as one of the tools to help diagnose diabetes but specifically stated that only standardized laboratory-based assays are appropriate for this purpose. The Endocrine Society concurred in a statement also released last year. (See the article ADA recommends A1c to diagnose diabetes and pre-diabetes.)
These organizations, however, do not recommend the POC versions of A1c tests for screening or diagnosis at this time because the performance of the assays currently available is more variable than laboratory-based tests. In addition, issues with some commercial POC A1c tests were reported in a study published in the journal Clinical Chemistry in January 2010. In that study, some of the assays evaluated did not meet the criteria required for screening or diagnosis.
While the performance level of POC A1c tests is adequate for monitoring purposes, it is advised that screening for and diagnosis of diabetes be performed using laboratory-based A1c tests, fasting glucose tests, or glucose tolerance tests.
If you or someone you know decides to participate in diabetes testing offered as part of a community screening program outside of a laboratory, know the limitations of the A1c point-of-care test. If you think you have diabetes or have concerns about your risk, consult your doctor and ask whether you need to be evaluated using an appropriate test.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
(December 7, 2010) Rob Stein. Diabetes Screenings Stir Concern. Washington Post. Available online at http://www.washingtonpost.com/wp-dyn/content/article/2010/12/06/AR2010120607549.html?sid=ST2010120701976 through http://www.washingtonpost.com. Accessed January 2011.
American Diabetes Association. Executive summary: standards of medical care in diabetes—2010. Jan 2010. Diabetes Care 33: S4-S10.
(January 2010) The Endocrine Society Statement on the use of A1c for Diabetes Diagnosis and Risk Estimation. Available online at http://www.endo-society.org/advocacy/loader.cfm?csModule=security/getfile&pageid=30809 through http://www.endo-society.org. Accessed January 2011.
Erna Lenters-Westra and Robbert J. Slingerland. Six of Eight Hemoglobin A1c Point-of-Care Instruments Do Not Meet the General Accepted Analytical Performance Criteria. Clinical Chemistry. 2010;56:44-52. Available onlien at http://www.clinchem.org/cgi/content/full/56/1/44 through http://www.clinchem.org. Accessed January 2011.