CGM: Continuous Glucose Monitor

 2016-08-03

Today’s CGM—continuous glucose monitor—technology put diabetes management into the 21st century. This small wearable device provides people with diabetes the information they need to make daily management decisions.

Improving both our short and long-term health and safety, CGMs should be considered the standard of care for anyone of any age with any type of diabetes.

What is a CGM?

A CGM is a small wearable device that tracks your glucose levels in real-time throughout the day and night. CGMs measure the glucose (sugar) in the interstitial fluid of your body fat compared to your blood glucose monitor (BGM) which measures the glucose in your blood.

At any moment—without pricking your finger—you can see what your glucose level is. You can also see what direction it’s headed in thanks to simple up, down, or sideways arrows.

With personalized settings, CGMs can alert you to high or low levels while also charting your glucose levels about every 5 minutes on a graph on your smartphone or separate receiver device.

Compared to checking your blood sugar with a drop of blood on a test strip, the information a CGM can provide both you and your healthcare team can have a huge impact on your diabetes management. CGM technology can help you make more thoughtful decisions around food, exercise, insulin, and medications. The insights you gain from using a CGM can improve your safety and help you reach your A1c and time-in-range goals.

*Watch this video to learn more about the differences between readings from your CGM vs. your BGM. 

How a CGM Works

While each brand of CGM technology works slightly different, they have many similarities. (*Most of the details described below do not apply to Senseonics’ implantable Eversense CGM technology.)

  • Most CGM sensors consist of three parts: sensor (which sits in the skin), the transmitter (sits above the skin), the receiver (either your Smartphone or a handheld device that receives blood sugar data).
  • Most CGM sensors (a very thin wire-like piece) sit in subcutaneous tissue (body fat). The sensor is usually inserted with an easy at-home application device that inserts the sensor with a fine needle. The needle instantly retracts, leaving the sensor in place.
  • The visible portion of a CGM is the transmitter, which is sits on top of the skin with an adhesive that holds the entire device in place. Many people apply a second adhesive on top of the entire transmitter to protect it and ensure it stays on.
  • CGM sensors can be placed in several areas of your body, depending on what is most comfortable for you: back of the arm, side/front torso, lower back, buttocks area, outer thigh, etc. Avoid spots where your body naturally bends a great deal, where clothing might cause irritation or be a burden.
  • The process of inserting the CGM sensor is easy and virtually painless. It can easily be done at home and takes just a few minutes from start to finish.
  • Most CGM sensors need to be replaced about every 2 weeks—this varies slightly depending on brand and model.

The Benefits of a CGM

A few of the benefits of using a CGM include:

  • See your glucose level at any moment without pricking your finger
  • See the direction of your glucose level: rising/falling, gradually/quickly
  • Learn how/when your body responds to food, activity, insulin, medication, hormones, stress, etc.
  • Customizable settings that alert you when your blood sugar falls below a certain level
  • Customizable settings that alert you when your blood sugar rises above a certain level
  • Catch and treat high glucose levels sooner
  • Catch and treat low glucose levels sooner
  • Help you reach your overall A1c and blood sugar goals
  • Learn what percentage of the day you are in/above/below your goal ranges (also known as “time-in-range” or TIR)
  • Integrate your CGM with your insulin pump (with additional features for closed-loop systems)
  • Share your CGM data with your healthcare team easily from the app on your smartphone
  • Share your real-time CGM data with family or friends to see at any time on their smartphone
  • Review your glucose levels at any time with helpful graphs and reports

How do I get a CGM?

Getting a CGM starts with asking your doctor to write the prescription. Talk to your doctor about your device options and decide together which might be best for you. (Scroll further on this page for detailed tips on getting a CGM.)

Check what brands are covered under your insurance plan (including patients on Medicaid and Medicare). For example, Dexcom’s CGMs are covered by Medicare. Abbott’s FreesStyle Libre is also covered by Medicare for those who qualify.

To receive a CGM under Medicare or Medicaid, please contact your local state health exchange to check your eligibility.

Some brands also offer complimentary trial periods for new users, like Hello, Dexcom or MyFreeStyle Program. The MyFreeStyle Program allows eligible people to try either the FreeStyle Libre 14 Day System or the FreeStyle Libre 2 system. After your eligibility is determined, you’d request a prescription from your healthcare provider and get guided support from 14 days of emails tailored to your personal journey.

CGMs Available Today

Here are today’s available CGM brands and models. This technology has evolved rapidly over the last decade, improving in ease-of-use, accuracy, and connectivity with other technology.

Dexcom: G6

Dexcom’s current models include the G6. A leader in CGM technology, Dexcom has gradually reduced the overall size of the transmitter while increasing the accuracy and ease-of-use since the earlier models.

G6

  • Measures your blood sugar every 5 minutes
  • No finger-stick calibrations required
  • Communicates directly with your Smartphone or receiver
  • Integrates with Tandem T:slim and Omnipod insulin pumps
  • Integrates with the Tide Pool closed-loop system
  • Can predict oncoming lows
  • Can be used without an insulin pump
  • 2-hour warm-up period after inserting new sensor before usable
  • Sensor lasts 10 days

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Medtronic: Guardian Connect

Medtronic’s Guardian Connect has evolved over the years, improving in accuracy and ease-of-use. It is the only CGM option for those using Medtronic insulin pumps who want an integrated system.

  • Measures your blood sugar every 5 minutes
  • Requires finger-stick calibration twice per day
  • Communicates directly with your Smartphone or receiver
  • Integrates with 670, 770, (780G soon) Medtronic insulin pumps
  • Can be used without an insulin pump
  • 2-hour warm-up period after inserting new sensor before usable
  • Sensor requires charging
  • Sensors lasts 7 days
  • Integrates with the Tide Pool closed-loop system

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Abbott: Freestyle Libre 14-Day & Libre 2 & Libre 3

The Freestyle Libre technology is the only CGM available at your local pharmacy versus shipments directly from the manufacturer. It’s also the most affordable, making it more accessible to those without insurance coverage.

FreeStyle Libre 14-day

  • “Flash” glucose monitor which communicates readings when you swipe sensor with your smartphone or reader
  • No calibration or code entry required
  • Warm-up period of 1 hour
  • Collects glucose readings every minute
  • Easy sensor application process
  • Sensor lasts 14 days
  • LibreLink app includes glucose trends and patterns
  • Can share glucose readings with caregivers and loved ones with LibreLinkUp app 

FreeStyle Libre 2

  • Same small form factor and core features of the 14-day system
  • Also lasts 14 days
  • Greater accuracy than the 14-day system
  • Customizable real-time glucose alarms in Libre 2 smartphone app or reader

FreeStyle Libre 3

  • The smallest, thinnest CGM on the market
  • About the size of two stack pennies
  • Also lasts 14 days
  • Bluetooth range up to 33 feet
  • Customizable real-time glucose alarms in Libre 3 smartphone app or reader

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Senseonics: Eversense

The newest of CGM technology, the Eversense CGM system is implanted beneath the skin. Unlike other CGM technology, the sensor is entirely beneath the skin, without any visual puncture site, while the transmitter is simply placed above the sensor area with an adhesive.

  • Inserted by a doctor every 180 days (365-day sensor available in Europe)
  • Sensor implanted beneath the skin
  • Can remove the external transmitter without removing sensor
  • Transmitter provides on-body vibration alarms even if phone is out-of-range
  • Studies show it may be more accurate than any other existing CGM technology
  • Requires additional costs associated with doctor appointments and procedures
  • May be difficult to get because doctors must be trained by Senseonics for implantation procedure

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