Evaluation of hematocrit bias on blood glucose measurement with six different portable glucose meters

Introduction: Measurement and monitoring of blood glucose levels in hospitalized patients with por-table glucose meters (PGMs) is performed widely and is an essential part of diabetes monitoring, de-spite the increasing evidence of several interferences which can negatively bias the accuracy of mea-surements. The purpose of this study was to evaluate the effect of the hematocrit on the analytical performances of different PGMs as compared with a reference laboratory assay. Materials and methods: The effect of various hematocrit values (č0.20, č0.45 and č0.63 L/L) were assessed in three whole blood specimens with different glucose concentration (č1.1, č13.3, and č25 mmol/L) by using six different commercial PGMs. The identical samples were also tested with the laboratory reference assay (i.e., hexokinase). The percentage difference from the laboratory assay (%Diff) was calculated as follows: % Diff = average PGM value - value from laboratory assay x 100 / value from laboratory assay. Results: The %Diff of the six different PGMs were rather broad, and comprised between 56.5% and -34.8% in the sample with low glucose concentration (č1.1 mmol/L), between 40% and -32% in the sample with high glucose concentration (č13.3 mmol/L), and between –50% and 15% in the sample with very high glucose concentration (č25 mmol/L), respectively. It is also noteworthy that a very high hematocrit value (up to 0.63 L/L) generated a remarkable negative bias in blood glucose (-35%) as measured with the laboratory assay, when compared with the reference sample (hematocrit 0.45 L/L). Conclusion: The results of this analytical evaluation clearly confirm that hematocrit produces a strong and almost unpredictable bias on PGMs performances, which is mainly dependent on the different type of devices. As such, the healthcare staff and the patients must be aware of this limitation, especially in the presence of extreme hematocrit levels, when plasma glucose assessment with the reference laboratory t