Consensus Statement on the Worldwide Standardization of the Hemoglobin A1C Measurement
The American Diabetes Association, European Association for the Study of Diabetes, International Federation of Clinical Chemistry and Laboratory Medicine, and the International Diabetes Federation
- Consensus Committee*
- Address correspondence and reprint requests to Richard Kahn, PhD, American Diabetes Association, 1701 N. Beauregard St., Alexandria, VA 22311. E-mail: rkahn{at}diabetes.org
- ADAG, A1C-derived average glucose
- IFCC, International Federation of Clinical Chemistry and Laboratory Medicine
- NGSP, National Glycohemoglobin Standardization Program
The hemoglobin A1C (A1C) assay has become the gold-standard measurement of chronic glycemia for over two decades. Anchored in the knowledge that elevated A1C values increase the likelihood of the microvascular complications of diabetes (and perhaps macrovascular complications as well), clinicians have used A1C test results to guide treatment decisions, and the assay has become the cornerstone for the assessment of diabetes care.
The clinical world has assumed that the A1C assay reflects average glycemia over the preceding few months. However, the data supporting that premise are not exceptionally robust (1–5); glucose concentrations were not measured frequently enough to compute a true “average.” To gain a better understanding of the relationship between A1C and average blood glucose, an international study has been initiated to document this relationship, using frequent capillary measurements and continuous glucose monitoring. The results of this study will be known around September 2007. Although some clinicians are already providing patients with their “average blood glucose,” by simply converting the current A1C test results (6) to a term more relevant to the values obtained from patient self-monitoring, the …
