Evaluation of HbA1c stability in refrigerated blood samples: for how long are samples fit for use?

HbA1c is a key biomarker for diagnosing and monitoring diabetes, but its reliability may be affected by preanalytical conditions, including sample storage. This study evaluated the stability of HbA1c in whole-blood EDTA samples stored at 2-8 °C. A pooled blood sample from 65 anonymized leftover specimens was aliquoted and measured in triplicate using capillary electrophoresis (Minicap Flex Piercing, Sebia) over 20 days, with an additional measurement at day 35. Total Allowable Error (TEa ±4.9%) and Reference Change Value (RCV ±2.32 mmol/mol) were used to determine molecular stability. HbA1c remained analytically stable for up to 13 days in this specific setting. This finding, when validated in different conditions, may help laboratories to optimize the routine workflow.