Abstract
Background Continuous glucose monitoring-derived parameters are becoming increasingly important
in the treatment of people with diabetes. The aim of this study was to assess whether
these parameters, as calculated from different continuous glucose monitoring systems
worn in parallel, are comparable. In addition, clinical relevance of differences was
investigated.
Methods A total of 24 subjects wore a FreeStyle Libre (A) and a Dexcom G5 (B) sensor in parallel
for 7 days. Mean glucose, coefficient of variation, glucose management indicator and
time spent in different glucose ranges were calculated for each system. Pairwise differences
between the two different continuous glucose monitoring systems were computed for
these metrics.
Results On average, the two CGM systems indicated an identical time in range (67.9±10.2 vs.
67.9±11.5%) and a similar coefficient of variation; both categorized as unstable (38.1±5.9
vs. 36.0±4.8%). In contrast, the mean time spent below and above range, as well as
the individual times spent below, in and above range differed substantially. System
A indicated about twice the time spent below range than system B (7.7±7.2 vs. 3.8±2.7%,
p=0.003). This could have led to different therapy recommendations in approximately
half of the subjects.
Discussion The differences in metrics found between the two continuous glucose monitoring systems
may result in different therapy recommendations. In order to make adequate clinical
decisions, measurement performance of CGM systems should be standardized and all available
information, including the HbA1c, should be utilized.
Key words
Glucose management indicator - coefficient of variation - time above range - time
below range - time in range
