As is common with Sensors that monitor glucose, accuracy generally improves after the first day of use. While there are many theories as to why this occurs, it is generally thought that Sensors need to acclimate to their physiological environment following insertion during the first day of wear.   On the first day of wear, 99.5% of FreeStyle Libre system glucose results fall within Zone A and Zone B of the Consensus Error Grid with no fingerstick calibrations and 10.9 % Mean Absolute Relative Difference(MARD) compared to blood glucose testing.1  1Bailey I, MD. “Evaluation of the Accuracy of the Abbott Sensor Based Interstitial Glucose Monitoring System” Diabetes Technology & Therapeutics. July 2015.
*Data on File, Abbott Diabetes Care Inc, FreeStyle Libre 2 System Performance Data Sheet.