A new-generation continuous glucose monitoring system: improved accuracy and reliability compared with a previous-generation system

Abstract

Background: Use of continuous glucose monitoring (CGM) systems can improve glycemic control, but widespread adoption of CGM utilization has been limited, in part because of real and perceived problems with accuracy and reliability. This study compared accuracy and performance metrics for a new-generation CGM system with those of a previous-generation device.

Subjects and methods: Subjects were enrolled in a 7-day, open-label, multicenter pivotal study. Sensor readings were compared with venous YSI measurements (blood glucose analyzer from YSI Inc., Yellow Springs, OH) every 15 min (±5 min) during in-clinic visits. The aggregate and individual sensor accuracy and reliability of a new CGM system, the Dexcom(®) (San Diego, CA) G4™ PLATINUM (DG4P), were compared with those of the previous CGM system, the Dexcom SEVEN(®) PLUS (DSP).

Results: Both study design and subject characteristics were similar. The aggregate mean absolute relative difference (MARD) for DG4P was 13% compared with 16% for DSP (P<0.0001), and 82% of DG4P readings were within ± 20 mg/dL (for YSI ≤ 80 mg/dL) or 20% of YSI values (for YSI >80 mg/dL) compared with 76% for DSP (P<0.001). Ninety percent of the DG4P sensors had an individual MARD ≤ 20% compared with only 76% of DSP sensors (P=0.015). Half of DG4P sensors had a MARD less than 12.5% compared with 14% for the DSP sensors (P=0.028). The mean absolute difference for biochemical hypoglycemia (YSI <70 mg/dL) for DG4P was 11 mg/dL compared with 16 mg/dL for DSP (P<0.001).

Conclusions: The performance of DG4P was significantly improved compared with that of DSP, which may increase routine clinical use of CGM and improve patient outcomes.

FIG. 1.

Histograms of individual sensor mean absolute relative difference (MARD) for the Dexcom (top) G4 Platinum (DG4P) and (middle) SEVEN PLUS (DSP), with a log-normal curve superimposed on each distribution. (Bottom) The median of the values of the individual DG4P sensor MARD values was 12.5% compared with 14% for the DSP individual sensor MARD values. The interquartile range for the individual sensor MARD for the DG4P was 9–16% compared with 12–20% for the DSP. In brief, the histograms show that the individual sensor MARD distribution for the DG4P has been narrowed and shifted toward the left compared with the DSP.

FIG. 2.

The cumulative distribution functions of the individual sensor mean absolute relative difference (MARD) for the Dexcom G4 Platinum (DG4P) and SEVEN PLUS (DSP) showing the difference in individual sensor MARD between the two systems. Comparison of the two cumulative distribution function curves shows there are a higher proportion of DG4P sensors with lower MARDs than of the DSP sensors.