Traceability to a primary reference measurement procedure (ID-LCMS); A key step in validating the clinical accuracy and safety of hospital blood glucose monitoring systems

Objective: A key step in the evaluation of the accuracy of blood glucose monitoring systems (BGMS) is using a comparator method aligned to a high order definitive reference method. We describe how we achieved traceability to an isotope dilution liquid chromatography mass spectrometry (ID-LCMS) method. We used ID-LCMS to evaluate the accuracy and specificity of two hospital BGMS used in China. Method: ID-LCMS was used to verify the calibration alignment of the laboratory plasma hexokinase reference method using NIST standard reference material and clinical samples. The ID-LCMS aligned hexokinase method was used to evaluate the clinical accuracy of two BGMS in hospitalized patients. System accuracy was evaluated using Chinese consensus guidelines. BGMS accuracy was also assessed with interference factors known to be present in critically ill patients' blood. Results: The laboratory plasma hexokinase reference method was shown to calibrate closely with ID-LCMS. Two BGMS demonstrated good correlation with this reference method. Only one BGMS met the Chinese guidelines. The interference factors didn't influence this BGMS but adversely affected the clinical accuracy of the other. Conclusions: We advocate that our IDMS calibration alignment approach for ensuring the accuracy of the glucose reference method should be adopted in evaluations assessing the accuracy of blood glucose monitoring systems.