User`s guide

160 | Dexcom G4 PLATINUM Continuous Glucose Monitoring System
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Another estimate used to show the accuracy of the System is the
absolute percent difference. The absolute percent difference tells
you the percent difference or “distance” between the System and YSI
values, but does not tell you whether the System is reading, on average,
higher or lower than the YSI laboratory standard. The mean absolute
percent difference is the average “distance” (regardless if positive or
negative) between System readings and YSI values.
Accuracy measures in differences for both the Original and Software
505 Studies are based on 9152 and 2263 paired glucose results,
respectively; the data are summarized in Table 4. Table 4 is categorized
within CGM glucose ranges.
Original Study (SW10050): Overall, on average, the System reads
2.9% different (Mean Percent Difference) than the reference and 13.3%
absolute different (Mean Absolute Difference) than the reference values.
The Median Percent Difference shows that half of the time the System
reads 1.7% or less than the YSI blood glucose values and the Median
Absolute Percent Difference shows that half of the time the System
reads about 9.8% or less than the YSI blood glucose values.
Software 505 Study (SW10505): Overall, on average, the System
reads 2.5% different (Mean Percent Difference) than the reference and
9.0% absolute different (Mean Absolute Difference) than the reference
values. The Median Percent Difference shows that half of the time the
System reads 2.4% or less than the YSI blood glucose values and the
Median Absolute Percent Difference shows that half of the time the
System reads about 7.0% or less than the YSI blood glucose values.