Author Affiliations: Department of Internal Medicine, Division of Metabolism, Endocrinology, and Nutrition, University of Washington, Seattle.
The hemoglobin A1c (HbA1c) assay was first used more than 30 years ago as a marker of diabetes control. Despite its availability for 2 decades, HbA1c testing did not assume a central role in diabetes care until the publication of 2 major clinical trials. The Diabetes Control and Complications Trial (DCCT) and the UK Prospective Diabetes Study (UKPDS) demonstrated that HbA1c level strongly predicts risk of microvascular complications associated with type 1 and type 2 diabetes, respectively.1,2 Largely consequent to these findings, HbA1c level has become the primary basis for diabetes diagnosis, treatment decisions, and assessment of quality health care. As clinical application of HbA1c measurement expands, so does the need for caution in its interpretation and appreciation of its substantial limitations.
Rubinow KB, Hirsch IB. Reexamining Metrics for Glucose Control. JAMA. 2011;305(11):1132-1133. doi:10.1001/jama.2011.314