The Impact of Interfering Substances on Continuous Glucose Monitors Part 3: A Review of Non-Labeled Substances Influencing Continuous Glucose Monitor Readings.

Presented is a series of narrative reviews that summarize published information regarding the effect or potential effect of interfering substances on the accuracy of continuous glucose monitoring (CGM) devices. While drawing together what is currently known regarding this topic, the future direction in this field and clinical implications posed by polypharmacy on CGM performance are considered. This third in a series of articles lists substances that have been found to influence readings from specific continuous glucose monitor (CGM) models. Points covered include: (1) A review of non-labeled substances that have been found, through in vivo or in vitro assessment, to influence CGM readings; (2) A consideration of substances found to influence CGM readings to an extent that warrants further investigations to determine if a clinically significant in vivo interfering effect occurs at therapeutically or nutritionally relevant levels of a substance and, as such, would require labeling by the manufacturer; and (3) the possibility of predicting if a new medication or formulation is predisposed to influencing CGM readings, based on an assessment of chemical structure or chemical classification. Evidence suggests that a more systematic approach to interference testing would be of value in determining if additional labeling is required for currently marketed CGMs. It is possible that many of the substances reported have previously been assessed by manufacturers and are within acceptance criteria such that product labeling is not required according to currently recognized definitions of interference. Nevertheless, it would be beneficial for this information to be publicly disclosed.