Expert Access - Current Status and New Recommendations for HbA1c Testing

Eugenio Zabaleta

Randie R. Little, PhD

April 14, 2011
1:00-2:00 pm Eastern (U.S.) time



Current Status and New Recommendations for HbA1c Testing

Hemoglobin A1c (HbA1c) is an important indicator of outcome risk in patients with diabetes mellitus. The results of the Diabetes Control and Complications Trial (DCCT), published in 1993, showed direct correlation between HbA1c levels and risks for diabetic complications including retinopathy, nephropathy and neuropathy. This led to the incorporation of specific HbA1c goals into diabetes treatment recommendations; however, assay methods were not standardized and therefore HbA1c results were frequently not relatable to these guidelines. Thus, the NGSP began in 1996 to standardize HbA1c results to those of the DCCT.

The program not only certifies methods and laboratories but also monitors progress in the field using data from the College of American Pathologists surveys; the results have shown much success in reducing the variability of HbA1c. The IFCC Reference System provides metrological traceability of HbA1c to a higher-order method. The relationship between the IFCC and NGSP has been established and is monitored twice yearly.

There has been controversy over which numbers should be reported in clinical settings; much of the world will report IFCC numbers but the U.S. will continue to report NGSP (DCCT) %. HbA1c has recently been recommended for use in the diagnosis of diabetes. This recommendation further underscores the need for continued improvement in, and ongoing evaluation of, the quality of HbA1c testing.


Dr. Little is an Associate Professor in the Departments of Pathology & Anatomical Sciences and Child Health at the University of Missouri and is Director of the Diabetes Diagnostic Laboratory. She is the coordinator of the NGSP network, a member of the NGSP Steering Committee, and a member of the IFCC Integrated Project on HbA1c. She received her BS in 1973 from the State University of New York at Stony Brook and PhD in Biology at Florida State University in 1977 prior to joining the faculty at the University of Missouri in 1979. She has published approximately 100 articles in the area of diabetes testing. Her research interests include glycated hemoglobin (HbA1c) testing and standardization, evaluation and comparison of HbA1c methods, use of HbA1c for diabetes diagnosis and screening, and standardization of insulin and C-peptide measurement.

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