Recommendations on the Collection of Comparator Measurement Data in the Performance Evaluation of Continuous Glucose Monitoring Systems

• Published in: Journal of diabetes science and technology Vol. 19; no. 4; pp. 1072 - 1081
• Main Authors: Freckmann, Guido, Pleus, Stefan, Eichenlaub, Manuel, Eriksson Boija, Elisabet, Fokkert, Marion, Hinzmann, Rolf, Jendle, Johan, Klonoff, David C., Makris, Konstantinos, Nichols, James H., Pemberton, John, Selvin, Elizabeth, Tran, Nam K., Witthauer, Lilian, Slingerland, Robbert J.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.07.2025
• Subjects: Blood Glucose - analysis; Blood Glucose Self-Monitoring - instrumentation; Blood Glucose Self-Monitoring - methods; Blood Glucose Self-Monitoring - standards; Continuous Glucose Monitoring; Humans; standardization; clinical performance evaluation; comparator data requirements; continuous glucose monitoring; traceability
• ISSN: 1932-2968; 1932-3107
• DOI: 10.1177/19322968251336221

While current systems for continuous glucose monitoring (CGM) are safe and effective, there is a high degree of variability between readings within and across CGM systems. In current CGM performance studies, device readings are compared with glucose concentrations obtained with a comparator (“reference”) measurement procedure (usually capillary or venous glucose). However, glucose concentrations from capillary and venous samples can systematically differ, often by as much as 5 to 10%. Different comparator methods have shown biases of up to 8%, and comparator devices of the same brand can systematically differ by more than 5%. To address these issues, the Working Group on CGM of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC WG-CGM) recommends standardizing study procedures and the comparator measurement process in CGM performance studies. The majority of IFCC WG-CGM members recommend the use of capillary samples as reference, mainly because CGM readings will then be aligned better with results from self-monitoring of blood glucose (SMBG). Even with factory-calibrated CGM systems, manufacturers require CGM users to perform SMBG in some situations, eg, manual calibration, confirmation of extreme readings, discordance between CGM readings and symptoms of hyper- or hypoglycemia, or intermittent signal loss. Comparator devices should meet defined analytical performance specifications for bias and imprecision. Comparator bias can be reduced by retrospective correction of comparator values based on measurements with a method or materials of higher metrological order. Once manufacturers align CGM readings of their systems with comparator results using standardized procedures, variability across CGM systems will be reduced.