HbA1c Pitfalls: When the Number Lies
HbA1c Pitfalls: When the Number Lies Hemoglobinopathies, iron deficiency, CKD, and transfusions all break A1c. Here's when to trust it and when to use alternatives. HbA1c is the cornerstone of diabetes diagnosis and monitoring. But it measures glycated hemoglobin, which means anything that alters hemoglobin or RBC lifespan will alter the A1c —independent of blood glucose. In your patients with sickle cell trait, iron deficiency, chronic kidney disease, or recent transfusions, the A1c may be telling you a completely different story than what their glucometer shows. How A1c Works (and Why It Breaks) A1c measures the percentage of hemoglobin A molecules with glucose attached. It reflects average blood glucose over the preceding 2–3 months (the lifespan of an RBC). This works perfectly when RBC lifespan and hemoglobin structure are normal. When they're not, the test becomes unreliable. Conditions That Falsely LOWER A1c These conditions shorten RBC lifespan or increase RBC turno...