American Diabetes Association (ADA) Recommendations Regarding Glycated Hemoglobin Standardization

American Diabetes Association Position Statement. Tests of Glycemia in Diabetes. Diabetes Care 26:Diabetes Care 26:S106-S108, 2003

"The National Glycohemoglobin Standardization Program (http://web.missouri.edu/~diabetes/ngsp.html), sponsored in part by the American Diabetes Association to standardize A1C test determinations to DCCT values, began in mid-1996. On an annual basis, manufacturers of A1C test assay methods are awarded a "certificate of traceability to the DCCT reference method" if their assay method passes rigorous testing criteria for precision and accuracy. It is desirable that laboratories use only A1C test assay methods that have passed certification testing. It is also desirable that all laboratories performing A1C testing participate in the College of American Pathologists proficiency testing survey for A1C testing started in mid-1996, which uses whole-blood specimens. Regardless of the assay method type and specific analyte quantified, all results should be reported as "% HbA1c" or "% HbA1c equivalents."

"Proper interpretation of A1C test results requires that health care providers understand the relationship between test results and average blood glucose, kinetics of the A1C test, and specific assay limitations. Data from the DCCT relating A1C test results to mean plasma glucose levels appear in Table 1, but these data should be used with caution if the A1C test assay method is not certified as traceable to the DCCT reference method."

Table 1

* Mean blood glucose results are 10-15% lower. Most blood glucose meters are calibrated to read as plasma glucose.