Table 2

Strengths and limitations of rtCGM and isCGM systems

StrengthsLimitations
rtCGM
Dexcom G6 sensor
 • Indicated for use in children ≥2 years• Confirmatory SMBG is recommended when
 • 10-day sensor wear with single use automatic inserter - the CGM reading does not match symptoms,
 • Can be used to dose insulin without confirmatory testing in most circumstances - if there is no trend arrow displayed, or
 • Automatic transmission of glucose data to the user; no action required to obtain data - if the user suspects that the reading may be inaccurate.
 • Provides active alarms/alerts for current and impending hyperglycemia and hypoglycemia (allows for different settings for daytime and nighttime)• Cost is higher than isCGM
 • Predictive low glucose alert setting
 • Factory calibrated
 • Allows optional calibration when glucose data do not match symptoms or confirmatory SBMG
 • Real-time results can be shared with up to five individuals via G6 Mobile app (Android and iPhone)
 • Interoperability with other devices
 • Passive downloading with Dexcom Clarity software
 • No interference by acetaminophen
 • Meets Medicare coverage requirement
Dexcom G5 sensor
 • Indicated for use in children ≥2 years• 7-day sensor wear life
 • Can be used to dose insulin without confirmatory testing in most circumstances• Requires twice-daily calibration, the accuracy of which can be limited by poor user SMBG technique or less accurate SMBG
 • Provides active alarms/alerts for current and impending hyperglycemia and hypoglycemia• Confirmatory SMBG with all rtCGM and isCGM sensors is recommended when
 • Automatic transmission of glucose data to the user; no action required to obtain data - the CGM reading does not match symptoms,
 • Allows optional calibration when glucose data do not match symptoms or confirmatory SBMG - if there is no trend arrow displayed, or
 • Real-time results can be shared with up to five individuals via G5 Mobile app (iPhone and Android) - if the user suspects that the reading may be inaccurate.
 • Interoperability with other devices• Cost is higher than isCGM
 • Accurate across glucose levels 40–400 mg/dL• Acetaminophen interference
 • Medicare approved• Less optimal performance on day 1
Guardian 3
 • Automatic transmission of glucose data to the user; no action required to obtain data• Not indicated for use in children <7 years
 • Provides active alarms/alerts for current and impending hyperglycemia and hypoglycemia• Nonadjunctive—requires confirmatory fingerstick testing for insulin dosing
 • Allows optional calibration when glucose data do not match symptoms or confirmatory SBMG• 7-day sensor wear life
 • Integrates with insulin pumps (e.g., hybrid AP) and can be used as a stand-alone system• Requires twice-daily calibration, the accuracy of which can be limited by poor user SMBG technique or less accurate SMBG
• Best accuracy requires 3–4 calibrations per day; the Medtronic 670G may require >2 calibrations to stay in auto mode
• Stops displaying data with late calibrations, potentially leaving the patient without data or active alerts
• Suboptimal performance on day 1
• Cost is higher than isCGM
• Less optimal performance on day 1
• Acetaminophen interference
Enlite
 • Automatic transmission of glucose data to the user; no action required to obtain data• Not indicated for use in children <16 years
 • Provides active alarms/alerts for current and impending hyperglycemia and hypoglycemia• Nonadjunctive—requires confirmatory fingerstick testing for insulin dosing
 • Allows optional calibration when glucose data do not match symptoms or confirmatory SBMG• 6-day sensor wear life
 • Integrates with insulin pumps (e.g., hybrid AP)• Requires twice-daily calibration, the accuracy of which can be limited by poor user SMBG technique or less accurate SMBG
• Less optimal performance on day 1
• Cost is higher than isCGM
• Acetaminophen interference
Eversense
 • 90-day sensor wear• Not indicated for use in children <18 years
 • Automatic transmission of glucose data to the user; no action required to obtain data• Requires in-office surgical procedure
 • Sensor cannot be accidentally dislodged• Nonadjunctive—requires confirmatory fingerstick testing for insulin dosing
 • Provides active alarms/alerts for current and impending hyperglycemia and hypoglycemia• Requires twice-daily calibration, the accuracy of which can be limited by poor user SMBG technique or less accurate SMBG
 • Transmitter can be removed and reattached• Stops displaying data with late calibrations, potentially leaving the patient without data or active alerts
 • Vibratory on-body alerts via the transmitter to alert user to hypoglycemia and hyperglycemia, even without the smartphone in range• 24-h warm-up period after sensor insertion
 • Interoperability with other devices• Cost is higher than isCGM
 • Wireless upload to a browser-based application
 • No interference by acetaminophen
isCGM
FreeStyle Libre
 • Requires no daily calibration; however, fingerstick testing may still be needed in certain situations (see Limitations)• Not indicated for children <18 years (US)
 • Ease of use by the patient• No data available for the first 12 h during warm-up period*
 • Up to 14-day sensor wear (ex-U.S.) and up to 10 days in the U.S. version*• Does not have real-time sharing capabilities
 • Can be used to dose insulin without confirmatory testing under most circumstances• Not recommended for those with hypoglycemia unawareness
 • Results can be shared with clinician via LibreLink app (via Android phone only)• Does not provide alarms for current/impending glucose events
 • Can be used in children/adolescents 4–17 years (ex-U.S.)• Is a “passive” system—data not transmitted continuously from sensor; results are available only when the sensor is scanned with a reading device (however, this may not be a limitation in less intensively managed patients not on insulin)
 • Measures glucose 40–500 mg/dL• Full 24-h data can be captured and downloaded only if the sensor is scanned at least every 8 h
 • Can be used in pregnancy (ex-U.S.)• Does not allow for “recalibration” or detection of poor individual sensor function
 • No interference by acetaminophen• In the U.S., currently is indicated for adults only
 • Lower cost than rtCGM systems• Requires fingerstick confirmatory testing under the following conditions:
 • Medicare approved - Hypoglycemia (≤70 mg/dL)
 • Measures blood ketones with special test strips - Impending hypoglycemia
 - Rapidly changing glucose
 - Symptoms of low or high blood glucose
 - 12-h warm-up period
 - When symptoms do not match system readings or when inaccurate readings are suspected
• Accuracy in hypoglycemic and hyperglycemic ranges is suboptimal
• Does not currently connect to insulin pumps or other platforms (e.g., smart pens, apps)
  • AP, artificial pancreas; ex-U.S., outside the U.S.

  • *Recently approved in the U.S. for 14-day wear and 1-h warm-up period. Not currently available at the time of this publication.