CGM: Continuous Glucose Monitor


Today’s CGMs — continuous glucose monitors — put diabetes management into the 21st century. This small wearable device provides people with diabetes the blood sugar information we 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 blood sugar levels in real-time throughout the day and night. At any moment, without pricking your finger, you can see not only what your blood sugar level is but also what direction it’s headed in.

With personalized settings, CGMs can alert you to high or low levels while also charting your blood sugar 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 help you adjust your diabetes management regimen and improve your overall safety around highs and lows.

*Watch this video to learn more about the differences between readings from your glucose monitor vs. a CGM sensor.

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.
  • CGM sensors can be placed in several areas of your body, depending on what is most comfortable for the user: 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.
  • Varying based on brand and model, most CGM sensors need to be replaced every 2 weeks.

The Benefits of a CGM

A few of the benefits of using a CGM include:

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

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 2 & Libre 14-Day

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.

Libre 14-day

Actually a “flash” glucose monitor, it communicates readings when you swipe sensor with your Smartphone
No calibration required
Warm-up period of 1 hour
Easy sensor application process
Sensor lasts 14 days
Libre 2

Measures your blood sugar every minute
No calibration required
Greater accuracy than 10-day system
Warm-up period of 1 hour
Features 8-hour historical trend
Sensor lasts 14 days

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.

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 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.

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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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

The Benefits of Time-in-Range for Type 2 Diabetes with DCES Megan Muñoz

Learn how time-in-range benefits people with Type 2 diabetes with diabetes care and education specialist, Megan Muñoz! MORE

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

Researchers break down the importance of CGMs in understanding diabetes and how to tackle accessibility barriers among Hispanic adults. MORE

Real Life with a CGM: Stories & Interviews

Here are a few stories from people with diabetes and healthcare providers who’ve experienced the benefits CGM technology!

Getting Bizzy in the Kitchen with T2D

Diabetes didn't stop this blogger from creating mouthwatering recipes. In fact, her FreeStyle Libre made her life and staying Bizzy in the kitchen easier.MORE

FreeStyle Libre Improved My Diabetes Management

DiabeticFoodie's Shelby Kinnaird chats with Beyond Type 2 on how the FreeStyle Libre 14 day system made life with diabetes easier.MORE

My First Time Wearing the FreeStyle Libre

Liz started wearing a CGM for the first time in late 2019. Read why she answered "one thousand times yes" when asked if the FreeStyle Libre improved her life.MORE

Experiencing A Telehealth Appointment

Planning on using Libreview to go over your FreeStyle Libre 14 day system data in your telehealth appointment? Diabetes care and education specialist, Julia Blanchette, and Beyond Type 2 Project Manag...MORE

My First Time Prescribing A FreeStyle Libre

Anna Simos is a diabetes clinical research coordinator and diabetes care and education specialist (DCES) at Stanford University. Anna chats with Beyond Type 2 about the first time she prescribed a Fre...MORE

A Type 2 Makeover by the Freestyle Libre 14 Day System

Allan Avendaño, 43, is a makeup artist from the Los Angeles area who uses the Freestyle Libre 14 day system to manage Type 2 diabetes. Allan tells Beyond Type 2 how the CGM device gave him a Type 2 m...MORE

Freestyle Libre’s Positive Impact on my Culinary Career

Chef Robert Lewis shares his story on why starting the Freestyle Libre was "love at first swipe" and how the device positively impacted his culinary career. MORE

My First Time Using LibreView to Help Patients with T2D

Julia Blanchette discusses her first experiences using LibreLink and LibreView to help patients learn more about what impacts their diabetes, why CGM is valuable for people with Type 2 diabetes, and t...MORE

What My First Month with Freestyle Libre Taught Me about My Diabetes

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Like Having a Life Coach on My Arm

Rob Taub shares his story about why wearing the Freestyle Libre is like having a life coach on his arm and what he's learned about diabetes.MORE

Better Decisions, Better Data: My FSL Story

Matilde Gómez-Revilla Rosas was diagnosed with Type 2 diabetes in 2016. She shares her experiences with Freestyle Libre and how it helped her make better decisions about her diabetes. MORE

My First Freestyle Libre: Making Adjustments to T2D Care

John Ramos shares how he obtained his first Freestyle Libre on Medicare and made changes to his T2D, such as learning how to calculate carb ratios.MORE

Saying Goodbye to GERTI

UK Type 2 advocate, Ken Tait, talks about his brief use of the Freestyle Libre 2 and why T2Ds need better access to CGM.MORE

Lessons Learned from My First CGM Experience

U.K.-based Type 2 advocate, Ken Tait, shares his experience with the Freestyle Libre 2 and why people with T2D should use a CGM. MORE