CGM: Continuous Glucose Monitor

2018-12-12

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.

Research on the Benefits of Using a CGM

Research shows people with Type 2 diabetes who are on multiple daily insulin injection therapies (MDI) and used a CGM lowered their average A1C from 8.5 percent to 7.7 percent.
In contrast, those who tracked their glucose using a standard BGM were only able to lower their A1C from 8.5 percent to 8.0 percent. Better management = decreases the risks of complications.

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.

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 as of May 31, 2022
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

Nationwide Study in France Shows Dramatic Drop in DKA in Type 1 and Type 2 after Starting on FreeStyle Libre

The study included more that 70,000 patients living with diabetes and DKA rates were reduced by 52% for patients with T1D and 47% for patients with T2D.MORE

Abbott’s FreeStyle Libre 2 App Receives FDA Clearance

On August 2, 2021, the FDA approved the FreeStyle Libre 2 app for adults and children with diabetes, allowing user to access glucose readings directly from their iPhone.MORE

Dexcom: G5 & G6►

Dexcom’s current models include the G5 and 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.

Measures your blood sugar every 5 minutes
Does not require finger-stick calibration with a glucose monitor
Communicates directly with your Smartphone or receiver
Integrates with Tandem T:slim and Omnipod insulin pumps
Can be used without an insulin pump
2-hour warm-up period after inserting new sensor before usable
Sensor lasts 7 days

Has all the features of the G5
No calibration required
Easier sensor applicator than G5
Can predict oncoming lows
Sensors lasts 10 days
Integrates with the Tide Pool closed-loop system

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

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 90 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

Watch this video to learn more about the differences between blood glucose readings and sensor readings, watch the video by FreeStyle Libre system below.

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.

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 the 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.

➞Join the Beyond Type 2 Community!

Getting a CGM

While CGMs can help anyone improve their diabetes health, getting a CGM can come with some hurdles. Here are some tips for navigating that process.

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Why Won’t My Insurance Cover a Continuous Glucose Monitor?

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Using a CGM

CGM technology can provide you with so much more information about your blood sugar levels than a glucose monitor.

The Importance of “Time in Range” for Diabetes Management

Many healthcare providers are embracing time in range (TIR) as an important measure in helping patients manage their diabetes. MORE

Lowering Your A1c with the FreeStyle Libre 14 Day System

Your A1c helps you monitor your progress towards your glycemic goals. The FreesStyle Libre can help you get there. Read how this CGM can help you reach your diabetes goals.MORE

Using CGM to Reduce Low Glucose Events

Always a little dizzy or shaky? Your blood sugar may be low. Read our article on how a CGM could help you reduce low blood glucose episodes.MORE

The Importance of CGM for Insulin-Dependent Type 2 Diabetes

For people with insulin-dependent Type 2 diabetes, a CGM can be the turning point in reaching your diabetes goals. Learn why these devices can work for you and make living with diabetes easier.MORE

The Value of Professional CGM

Need help with your diabetes routine? Consider trying professional CGM (P-CGM). You and your doctor can use it to learn more about your Type 2 diabetes.MORE

Sharing Your CGM Data

You don't need to do diabetes alone. If you wear a CGM, read about sharing your data with your friends and family who help you manage Type 2 diabetes.MORE

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Researchers Find That CGMs Provide Insight On The Progression Of Type 2 Diabetes Among Hispanic Adults

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All About Time-in-Range

Time-in-range (TIR) is a measurement that tells you what percentage of the day your blood sugars are in your goal range.MORE

Why Won’t My Insurance Cover a Continuous Glucose Monitor?

Are you facing challenges getting insurance to cover a CGM? Here are some common reasons insurance denies CGM coverage and what you can do about it!MORE