Like insulin pumps, continuous glucose monitoring (CGM) systems all have certain basic properties in common. 

  • Features common to all CGM systems:

    • System includes a subcutaneous sensor, transmitter (Separate or built in).
    • Wireless system between transmitter and receiver.
    • Waterproof sensors/transmitters (receiver/display not waterproof).
    • Multiple on-screen trend graphs.
    • Direction and rate-of-change arrows
    • Mechanical device used to insert sensors.
    • Sensors may be re-usable; sensor life varies from person to person.
    • Warmup period (with no data) at beginning of sensor session.
    • Some lag time between blood glucose (fingerstick) and subcutaneous glucose (sensor) values.
    • Backlogged data reported to receiver/app when in range
    • Events such as food, insulin or activity can be logged
    • Insurance coverage varies from plan to plan.
    • Minimal skin irritation, even with prolonged sensor life.
    • 30-Day Money-Back guarantee

But each CGM also has unique features that make them better choices for certain individuals. Read our list of the pros and cons of some of the continuous glucose monitors available now.

Pros & Cons of the Senseonics Eversense Continuous Glucose Monitor

senseonics eversense cgm review

  • Unique Advantages: Pros

    • Approved Sensor life 90 days
    • Variety of vibrate & audio alerts via phone app
    • Transmitter vibrates for alerts when out of range of phone
    • Data back fills when away from phone/receiver
    • Real time alerts for high, low, rate of change, or predictive low
    • Not impacted by acetaminophen use
    • Real-time sharable data
    • Transmitter can be removed and replaced without sensor change
    • Least medical waste
  • Potential Drawbacks: CONS

    • Sensor insertion (and removal) requires incision in physician’s office 
    • 24 hour warm up period after insertion
    • Requires twice-daily calibration
    • Transmitter requires daily or bi-daily charging
    • Data upload not compatible with third party software
    • Not Medicare approved
    • Data not collected if transmitter not worn

Pros & Cons of the Freestyle Libre 14 hour Continuous Glucose Monitor

freestyle libre 14 day cgm review

  • Unique Advantages: Pros

    • No calibration needed
    • Sensor life 14 days
    • Single button press insertion
    • Low profile transmitter
    • Lowest cost
    • 1-hour warm up (shortest)
    • Glucometer built into reader
    • Reading updated every 60 seconds, recorded to memory every 15 minutes,
    • Sensor stores up to 8 hours of data if not read.
    • Reader accepts notes or events
    • Medicare approved
    • Data upload software
  • Potential Drawbacks: CONS

    • No realtime high/low alerts
    • Need to carry reader and scan sensor to get data
    • No “sharing” feature
    • Calibration not available to improve accuracy.
    • Widest inaccuracy in low glucose range
    • Reader requires up to 3 hour charge every 7 days
    • Freestyle software uploading can be confusing and reports are not interactive
    • May be impacted by Vitamin C and aspirin
    • Events must be entered at time of event (cannot back-enter)
    • Transmitter adhesive may not last 14 days

Pros & Cons of the Medtronic Guardian3 – 670G or Guardian Connect Continuous Glucose Monitor

medtronic 670G review

  • Unique Advantages: Pros

    • Available with 670G integration or Guardian Connect app (but not both)
    • Approved Sensor life 7 days (sensors may be reused)
    • Customizable alerts for different times and days
    • Single-button insertion
    • Vibrate & audio alerts only limited by phone’s options (Guardian Connect only)
    • Real time alerts for high, low, rate of change, or predictive low/high
    • Real-time sharable data (Guardian Connect only)
    • Sugar IQ companion app generates reports, indicates patterns/trends (Guardian Connect only)
  • Potential Drawbacks: CONS

    • 2 hour warm up time
    • Complicated taping procedure
    • Multiple tapes can cause skin skin issues
    • Requires at least once calibration every 12 hours
    • Stops generating data if not calibrated
    • Transmitter requires 10-20 minute charge every 7 days
    • Only compatible with Medtronic pumps, apps, and uploading
    • Guardian Connect Apps available only on Apple devices
    • Impacted by acetaminophen use
    • Fair accuracy

Pros & Cons of the Dexcom G6 Continuous Glucose Monitor

dexcom G6 cgm review

  • Unique Advantages: Pros

    • No calibration needed
    • Calibration available to improve accuracy
    • Approved Sensor life 10 days
    • Customizable alerts for different times and days
    • Single button push insertion
    • Vibrate & audio alerts
    • Interoperability to Tandem X2 pump
    • Sends data to phone app (and apple watch), receiver, or pump.
    • Real time alerts for high, low, rate of change, predictive urgent low
    • “Always sound” feature can sound alerts when phone is on silent.
    • Not impacted by acetaminophen use
    • Real-time sharable data
    • Approved for children over 2
    • Medicare approved
    • Clarity companion app automatically uploads data, generates reports
  • Potential Drawbacks: CONS

    • Transmitter must be replaced every 3 months 
    • Lots of medical waste with sensor inserters
    • Occasional delays receiving product orders and technical support
    • Re-use of sensors involves a difficult process
    • Costly sensors and transmitters