User`s guide
Dexcom G4 PLATINUM User’s Guide | 159
Table 3-B. Concurrence of CGM Readings and YSI
Values (Software 505 Study)
CGM
(mg/dL)
YSI (mg/dL)
Row percentage of matched pairs in each CGM glucose range
< 40
40-
60
61-
80
81-
120
121-
160
161-
200
201-
250
251-
300
301-
350
351-
400
> 400
Number
of Paired
CGM-YSI
< 40 6% 83% 11% 0% 0% 0% 0% 0% 0% 0% 0% 18
40-60 2% 74% 22% 3% 0% 0% 0% 0% 0% 0% 0% 120
61-80 0% 19% 68% 13% 0% 0% 0% 0% 0% 0% 0% 226
81-120 0% 0% 19% 72% 8% 1% 0% 0% 0% 0% 0% 347
121-160 0% 0% 0% 17% 72% 11% 0% 0% 0% 0% 0% 246
161-200 0% 0% 0% 0% 25% 59% 16% 0% 0% 0% 0% 286
201- 250 0% 0% 0% 0% 0% 16% 70% 13% 1% 0% 0% 376
251- 300 0% 0% 0% 0% 0% 2% 16% 61% 14% 7% 0% 281
301- 350 0% 0% 0% 0% 0% 0% 2% 28% 59% 10% 1% 229
351- 400 0% 0% 0% 0% 0% 0% 0% 4% 47% 45% 5% 152
> 400 0% 0% 0% 0% 0% 0% 0% 0% 20% 38% 42% 45
Accuracy Relative to YSI
Accuracy between matched pairs was also estimated by calculating the
percent difference between the System reading and the YSI value. For
example, if the YSI value is 100 mg/dL and the System reading is 90
mg/dL, a 10% difference between the System and the YSI is reported.
The System and YSI values were compared by pairing the System
reading that fell immediately after the YSI value was collected.
In the example above, the System reading is less than the YSI value, so
the percent difference reading is negative. The mean percent difference
is the average of all positive and negative percent differences between
the two devices; it tells you if the System reads higher or lower on
average than the YSI within each glucose range.