Table 3

Accuracy of FreeStyle Navigator continuous glucose monitor during early and late pregnancy

MeasureOverallEarly pregnancyLate pregnancyP value
Data points1,923966957
 Target range (70–180 mg/dL)1,609794815
 Hypoglycemia (<70 mg/dL)247132115
 Hyperglycemia (>180 mg/dL)674027
Mean absolute relative difference (%)
Overall13.314.6811.930.15
 Target range12.1613.4410.92
 Hypoglycemia21.9123.7019.84
 Hyperglycemia9.259.528.86
Median absolute relative difference (%)
Overall11.4212.859.890.21
 Target range10.4612.078.99
 Hypoglycemia21.5822.7520.33
 Hyperglycemia9.069.278.73
International Standards Organization criteria*
Overall79.6276.4082.860.33
 Target range81.5478.2184.79
 Hypoglycemia61.9458.3366.09
 Hyperglycemia98.5110096.30
Error grid analysis, %
 A–Clinically accurate78.9475.7582.450.55
 B–Within 20% of reference15.7017.9013.17
 C–Overcorrection error000
 D–Failure to detect hypoglycemic or hyperglycemic excursion5.366.354.39
 E–Unsafe control000
  • *International Standards Organization criteria are based on the percentage CGM measurements within 15 mg/dL from reference when the reference plasma glucose is ≤75 mg/dL or within 20% from reference when the reference plasma glucose is >75 mg/dL.

  • P value refers to error grid analysis A + B combined values of 93.6% in early pregnancy vs. 95.6% in late pregnancy.