Accurate blood glucose measurements are important during normal daily activities, even more so during exercise. The accuracy of glucose sensors measuring interstitial glucose concentrations using fluorescence or glucose-oxidase techniques may be variable in different circumstances.
Prospective, observational study in twenty-five persons with diabetes during mountain biking in the Sierra Nevada for 6 days, and during normal daily activities for 6 days. We investigated the performance of two sensors, the Free Style Libre (FSL; glucose oxidase based) and the Eversense (fluorescence based), compared to the capillary based Precision NeoPro (FSLCstrip). Multiple paired measurements were performed. Data was assessed both with Parkes error grids and with direct comparisons of absolute and relative differences in point measurements.
Correlations during mountain biking (970 paired measurements): Eversense vs FSLCstrip, y=1.010x-9.88; r = 0.883 (98.3% in Parkes error grid zones A+B (73.2 + 25.1%), FSL vs FSLCstrip: y=1.21x-10.13; r = 0.917 (98.2% in Parkes error grid zones A+B(73.9 + 24.3%). During normal daily activities(896 paired measurements): Eversense vs FSLCstrip: y=0.96x-0.11; r = 0.920 (98.8% in Parkes error grid zones A+B (81.9 + 16.9%), FSL vs FSLCstrip: y=1.07x-9.57, r = 0.937 (99.9% in Parkes error grid zones A+B (87.1 + 12.8%). Differences of >15% between the measurement techniques were present during the exercise week in 35 – 65%; during normal daily activities in 25 – 58%.
During mountain biking , interstitial glucose readings with both the Eversense and the FSL were less accurate compared to measurements during normal daily activities.