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

Abstract

Introduction: Measurement and monitoring of blood glucose levels in hospitalized patients with portable glucose meters (PGMs) is performed widely and is an essential part of diabetes monitoring, despite the increasing evidence of several interferences which can negatively bias the accuracy of measurements. The purpose of this study was to evaluate the eff ect of the hematocrit on the analytical performances of diff erent PGMs as compared with a reference laboratory assay. Materials and methods: The eff ect of various hematocrit values (~0.20, ~0.45 and ~0.63 L/L) were assessed in three whole blood specimens with diff erent glucose concentration (~1.1, ~13.3, and ~25 mmol/L) by using six diff erent commercial PGMs. The identical samples were also tested with the laboratory reference assay (i.e., hexokinase). The percentage diff erence from he 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 diff erent PGMs were rather broad, and comprised between 56.5% and -34.8% in the sample with low glucose concentration (~1.1 mmol/L), between 40% and -32% in the sample with high glucose concentration (~13.3 mmol/L), and between -50% and 15% in the sample with very high glucose concentration (~25 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 confi rm that hematocrit produces a strong and almost unpredictable bias on PGMs performances, which is mainly dependent on the diff erent 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 technique might be advisable.