One HbA1c Measurement Does Not Tell the Whole Story – 5 Case Studies

Kristina Jackson Behan

doi:10.29074/ascls.28.4.232

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Kristina Jackson Behan, PhD, MLS (ASCP)⇑
1. Clinical Laboratory Sciences Program, University of West Florida, Pensacola, FL

Address for Correspondence: Kristina Jackson Behan, PhD, MLS (ASCP), Clinical Laboratory Sciences Program, University of West Florida, 11000 University Parkway, Pensacola, FL 32514, 850-474-3060, kbehan{at}uwf.edu

Abstract

Hemoglobin A1c is produced by an interaction between intracellular glucose and hemoglobin. This is a dynamic process, because glucose values vary and RBCS have a limited lifespan. Hemoglobin A1c testing is performed to monitor glycemic control in patients with diabetes mellitus. The ADA recommends testing HbA1c twice a year in patients with good control, and more often in patients who do not meet their goals. MLS/CLS students are required to have an understanding of the relationship between HbA1c, plasma glucose and time. Case studies are valuable teaching tools to illustrate the dynamic nature of HbA1c formation. This work shows 4 months of serial HbA1c and glucose measurements in 5 individuals with type 2 diabetes mellitus. A stepwise increase or decrease of HbA1c is seen in subjects who have a change in their glycemic control, illustrating why one HbA1c result does not tell the whole story.

ABBREVIATIONS: eAG - estimated average glucose, ADA - American Diabetes Association, HbA1c - Hemoglobin A1c