Dexcom G4 User Manual page 130

a reliable laboratory method, the Yellow Springs Instrument 2300 STAT Plus™
Glucose Analyzer. This instrument is referred to as the "YSI." Readings from
the System were reported every 5 minutes and paired with YSI values in order
to characterize how well the System readings agreed with laboratory standard
blood glucose results. The remainder of the study took place at home,
the System performance was also paired with the comparative LifeScan
OneTouch Ultra2 meter results, and that is referred to as the 'SMBG'.
Agreement
Agreement between the System and blood glucose values is characterized
using paired System and YSI values. The System and YSI results were
compared by pairing the YSI blood glucose value to a System glucose reading
that occurred immediately after the YSI was collected.
The agreement of the System to blood glucose value was assessed by
calculating the percentage of System readings that were within 20%, 30%
and 40% of the YSI values. For readings less than or equal to 80 mg/dL (4.4
mmol/L) the absolute difference in mg/dL (mmol/L) between the two glucose
results was calculated. For values greater than 80 mg/dL (4.4 mmol/L) the
absolute percent difference (%) from the YSI values was calculated. The
percentages of total readings within 20 mg/dL (1.1 mmol/L) or 20%, 30 mg/dL
(1.7 mmol/L) or 30% or 40 mg/dL (2.2 mmol/L) or 40% were then calculated in
Table 1.
The total number of data pairs considered in this analysis was 9152. Of these,
eighty two percent (82%) of the System readings fall within ± 20 mg/dL (1.1
mmol/L) of the YSI blood glucose values (≤ 80 mg/dL or 4.4 mmol/L) and within
±20% of YSI blood glucose values (> 80 mg/dL or 4.4 mmol/L).
Table 1. System Agreement to YSI within YSI Glucose Ranges
YSI Glucose
Number
Range
of paired
mg/dL
CGM-YSI
(mmol/L)
Overall
40-80
(2.2-4.4)
NOTE: CGM readings are within 40 to 400 mg/dL (2.2-22.2 mmol/L), inclusive.
130 | Dexcom G4 Continuous Glucose Monitoring System
Percent
within 20/20%
YSI
9152 82%
1351 83%
Percent Percent
within 30/30% within 40/40%
YSI YSI
92% 97%
94% 98%