The Effects of Storage and Additives on Postmortem HbA1c Measurements

HbA1c is used in forensic toxicology to identify undiagnosed diabetes mellitus (DM) and those with poor glycemic control prior to death. HbA1c is typically measured in whole blood collected in tubes containing ethylenediaminetetraacetic acid (EDTA). The effect of other additives, including sodium fluoride (NaF), is unclear. Furthermore, the assessment of short- and long-term stability of HbA1c has produced conflicting results. In this study, we collected paired postmortem blood samples in EDTA and NaF tubes (n = 142) to assess their comparability for HbA1c measurement. Stability was assessed by measuring HbA1c at baseline, 2, 3, and 4 weeks postcollection (stored at 4°C) and at 2, 4, 6, and 12 months postcollection (stored at -20°C). We found no significant difference in HbA1c between the two preservatives at any of the time points indicating NaF is a suitable preservative for HbA1c measurement. We also determined that DM status, postmortem interval, and decomposition had no effect on stability.