When HbA1c Lies: Recognizing and Managing HbA1c-Glucose Discordance in Clinical Practice.

Hemoglobin A1c (HbA1c) remains a cornerstone of glycemic assessment in diabetes mellitus care, yet discordance between HbA1c and measured glucose values is common in clinical practice. Failure to recognize this discordance can lead to inappropriate treatment escalation, increased hypoglycemia risk, and patient distress. This article reviews the biological and clinical factors that contribute to HbA1c-glucose discordance and translates these findings into practical strategies for routine care. Common causes include iron deficiency, chronic kidney disease, altered red blood cell turnover, hemoglobin variants, and rapid changes in glycemia. A stepwise, practice-oriented framework is presented to guide clinicians in evaluating discordant glycemic data using targeted laboratory testing and continuous glucose monitoring metrics. Emphasis is placed on avoiding reflexive medication intensification and using glucose monitoring data to individualize treatment decisions. The role of interdisciplinary care and patient-centered communication is also highlighted.