title: Rate-of-Change Dependence of the Performance of Two CGM Systems During Induced Glucose Swings.
abstract: BACKGROUND
  The accuracy of continuous glucose monitoring (CGM) systems is often assessed with respect to blood glucose (BG) readings. CGM readings are affected by a physiological and a technical time delay when compared to BG readings. In this analysis, the dependence of CGM performance parameters on the BG rate of change was investigated for 2 CGM systems.
  
  
  METHODS
  Data from a previously published study were retrospectively analyzed. An established CGM system (Dexcom G4, Dexcom, San Diego, CA; system A) and a prototype system (Roche Diagnostics GmbH, Mannheim, Germany; system B) with 2 sensors each were worn by 10 subjects in parallel. Glucose swings were induced to achieve rapidly changing BG concentrations. Mean absolute relative differences (MARD) were calculated in different BG rate-of-change categories. In addition, sensor-to-sensor precision was assessed.
  
  
  RESULTS
  At BG rates of change of -1 mg/dl/min to 0 mg/dl/min and 0 mg/dl/min to +1 mg/dl/min, MARD results were 12.6% and 11.3% for system A and 8.2% and 10.0% for system B. At rapidly changing BG concentrations (<-3 mg/dl/min and ≥+3 mg/dl/min), higher MARD results were found for both systems, but system B was less affected (system A: 24.9% and 29.6%, system B: 10.6% and 16.3%). The impact of rate of change on sensor-to-sensor precision was less pronounced.
  
  
  CONCLUSIONS
  Both systems were affected by rapidly changing BG concentrations to some degree, although system B was mostly unaffected by decreasing BG concentrations. It would seem that technological advancements in CGM systems might allow for a more precise tracking of BG concentrations even at rapidly changing BG concentrations.
authors: Institut für Diabetes-Technologie Forschungs- und Entwicklungsgesellschaft mbH an der Universität Ulm, Ulm, Germany stefan.pleus@uni-ulm.de.
authors: Stefan
authors: S
authors: Pleus
authors: Roche Diagnostics GmbH, Mannheim, Germany.
authors: Michael
authors: M
authors: Schoemaker
authors: Roche Diagnostics GmbH, Mannheim, Germany.
authors: Karin
authors: K
authors: Morgenstern
authors: Roche Diagnostics GmbH, Mannheim, Germany.
authors: Günther
authors: G
authors: Schmelzeisen-Redeker
authors: Institut für Diabetes-Technologie Forschungs- und Entwicklungsgesellschaft mbH an der Universität Ulm, Ulm, Germany.
authors: Cornelia
authors: C
authors: Haug
authors: Institut für Diabetes-Technologie Forschungs- und Entwicklungsgesellschaft mbH an der Universität Ulm, Ulm, Germany.
authors: Manuela
authors: M
authors: Link
authors: Institut für Diabetes-Technologie Forschungs- und Entwicklungsgesellschaft mbH an der Universität Ulm, Ulm, Germany.
authors: Eva
authors: E
authors: Zschornack
authors: Institut für Diabetes-Technologie Forschungs- und Entwicklungsgesellschaft mbH an der Universität Ulm, Ulm, Germany.
authors: Guido
authors: G
authors: Freckmann
mesh_terms: D000328:Adult; D000465:Algorithms; D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring / Q000295:instrumentation* / Q000379:methods; D002138:Calibration; D003920:Diabetes Mellitus / Q000097:blood* / Q000175:diagnosis; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
chemical_list: D001786:Blood Glucose
keywords: MARD; PARD; accuracy; continuous glucose monitoring; rate of change