New features and performance of a next-generation SEVEN-day continuous glucose monitoring system with short lag time

Diabetes Technol Ther. 2009 Dec;11(12):749-55. doi: 10.1089/dia.2009.0075.


Background: The purpose of this study was to evaluate new features and performance of the SEVEN PLUS System (DexCom, Inc., San Diego, CA), a real-time continuous glucose monitoring (CGM) device. This study is the first to evaluate the SEVEN PLUS device.

Methods: Fifty-three subjects were enrolled at three U.S. centers; 43 (81%) of the subjects had type 1 diabetes mellitus, and 10 (19%) had insulin-requiring type 2 diabetes mellitus. Subjects inserted and wore either one or two sensors for 7 days. A subgroup (n = 18) wore two sensors to track precision. Subjects participated in one 8-h in-clinic session with blood draws every 15 min on study Day 1, 4, or 7 to collect laboratory reference YSI instrument (YSI, Yellow Springs, OH) and self-measured plasma glucose (SMPG) reference measurements. For the remainder of the week, CGM was used as an adjunct to SMPG during home use.

Results: The overall median absolute relative difference (ARD) versus YSI was 13.0%. Zones A and B of the Clarke Error Grid of CGM measurements were 73.8% and 22.1%, respectively. Precision ARD was 15.3 +/- 6.2% (mean +/- SD). The median ARD versus SMPG was 12.1%. Sensor life (89% lasted 7 days) was improved compared to the SEVEN device. The lag time obtained with various statistical measures between CGM and YSI were similar and estimated as a median of 8 min (interquartile range, 11 min) using the Pearson correlation coefficient. No serious adverse events or infectious complications were reported.

Conclusions: The performance of this new system compares favorably to the previous SEVEN device in terms of accuracy, precision, lag time, sensor life, and rate of data capture.

Publication types

  • Clinical Trial
  • Multicenter Study

MeSH terms

  • Adult
  • Blood Glucose / analysis*
  • Blood Glucose Self-Monitoring / instrumentation*
  • Blood Glucose Self-Monitoring / methods
  • Blood Glucose Self-Monitoring / standards
  • Calibration
  • Diabetes Mellitus, Type 1 / blood*
  • Diabetes Mellitus, Type 2 / blood*
  • Equipment Design
  • Female
  • Humans
  • Male
  • Middle Aged
  • Monitoring, Ambulatory / instrumentation
  • Monitoring, Ambulatory / methods*
  • Monitoring, Ambulatory / standards
  • Prospective Studies
  • Reference Values
  • Reproducibility of Results
  • Time Factors
  • United States


  • Blood Glucose