Freestyle Libre 14 day User Manual page 115

Overall Accuracy against YSI reference
Accuracy was measured by comparing the absolute relative difference between the System and
reference YSI glucose values. The absolute relative difference measures the level of disagreement
between the System and the reference value, but does not tell you whether the System glucose
value was, on average, higher or lower than the reference glucose value. The Mean Absolute Relative
Difference gives an indication of the average percent disagreement between the CGM
and the reference. Table 3 shows the overall absolute difference measure. Overall the Mean Absolute
Relative Difference was 9.4% for the comparison with YSI reference. The Median Absolute Relative
Difference shows that half of the time the System was within 7.4% of the YSI reference.
Table 3: Difference Measures with YSI Reference
Number of
CGM-Reference Pairs
9725
Agreement with BG Levels
Agreement between the System and capillary blood glucose values (BG) as measured by the Reader's
built-in meter was characterized by using paired System CGM and BG value. The accuracy of CGM
versus BG value was assessed by calculating the percentage of System readings that were within 15%,
20%, 30% and 40% for BG values 80 mg/dL and above, and within 15 mg/dL, 20 mg/dL, 30 mg/dL
and 40 mg/dL for values below 80 mg/dL. The results are presented in Table 4 for BG values. Overall
87.0% of results were within ±20 mg/dL / 20% of BG values.
Median Absolute Relative
Difference (%)
7.4
Mean Absolute Relative
Difference (%)
9.4
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