title: New features and performance of a next-generation SEVEN-day continuous glucose monitoring system with short lag time.
abstract: 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.
authors.affiliation: AMCR Institute, Escondido, California 92026, USA. tbailey@amcrInstitute.com
authors.forename: Timothy
authors.initials: T
authors.lastname: Bailey
authors.forename: Howard
authors.initials: H
authors.lastname: Zisser
authors.forename: Anna
authors.initials: A
authors.lastname: Chang
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D002138:Calibration; D003922:Diabetes Mellitus, Type 1 / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D011446:Prospective Studies; D012016:Reference Values; D015203:Reproducibility of Results; D013997:Time Factors; D014481:United States
chemical_list: D001786:Blood Glucose