FreeStyle Navigator Continuous Glucose Monitoring System with TRUstart algorithm, a 1-hour warm-up time

J Diabetes Sci Technol. 2011 Jan 1;5(1):99-106. doi: 10.1177/193229681100500114.


Background: The first-generation FreeStyle Navigator® Continuous Glucose Monitoring System (FreeStyle Navigator CGM) requires a 10 h warm-up period to avoid inaccurate glucose readings caused by sensor insertion trauma and wound-healing processes. The performance of a second-generation FreeStyle Navigator CGM that begins reporting glucose 1 h after sensor insertion is described.

Methods: Second-generation FreeStyle Navigator CGM performance was evaluated in an in-clinic study using the YSI Model 2300 STATPlus Glucose Analyzer as reference with 47 subjects with type 1 diabetes. The reference readings were taken at 15 min intervals, and the study was designed to emphasize the first 10 h of use.

Results: The second-generation FreeStyle Navigator CGM exhibited continuous glucose error grid analysis ratings of 93.7% "clinically accurate," 3.6% "benign errors," and 2.8% "clinical errors" and a mean and median absolute relative difference of 14.5% and 10.7%, respectively. The second-generation algorithm detected signal instability in the first 10 h of use and suspended the reporting of 14.1% of first day continuous glucose readings. The clinical accuracy of the second-generation FreeStyle Navigator CGM was similar for the first 10 h versus subsequent hours, with 92.6% and 94.2% "clinically accurate" readings, respectively.

Conclusion: The warm-up period for the second-generation FreeStyle Navigator CGM was reduced from 10 to 1 h, with minimal interruption of glucose reporting and without sacrificing clinical performance.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Algorithms*
  • Blood Glucose / analysis*
  • Blood Glucose Self-Monitoring / instrumentation
  • Blood Glucose Self-Monitoring / methods
  • Blood Glucose Self-Monitoring / standards
  • Calibration
  • Clinical Alarms / standards
  • Diabetes Mellitus, Type 1 / blood*
  • Diabetes Mellitus, Type 1 / complications
  • Diabetes Mellitus, Type 1 / epidemiology
  • Diabetes Mellitus, Type 1 / therapy
  • Equipment Design
  • Humans
  • Hypoglycemia / diagnosis
  • Hypoglycemia / epidemiology
  • Hypoglycemia / etiology
  • Middle Aged
  • Monitoring, Ambulatory / instrumentation*
  • Monitoring, Ambulatory / methods
  • Monitoring, Ambulatory / standards
  • Sensitivity and Specificity
  • Time Factors


  • Blood Glucose