Key takeaways
- Continuous glucose monitoring (CGM) tracks glucose levels every 1 to 5 minutes, helping people with diabetes understand how food, sleep, and exercise affect their blood sugar without frequent fingersticks.
- The Dexcom G7, G7 15 Day, and FreeStyle Libre 3 Plus have similar accuracy and connect to smartphones, smartwatches, and insulin pumps.
- Both CGM systems typically cost $20 or less per month with commercial insurance, and pharmacy savings cards or copay programs are available for those without coverage or with high copays.
Continuous glucose monitoring (CGM) regularly tracks glucose levels, helping people with diabetes manage their condition without multiple daily fingersticks.
CGMs provide useful data on how food, sleep, and exercise affect glucose levels, which can motivate people to make lifestyle changes to improve their health.
This review explores the Dexcom G7, G7 15 Day, and the FreeStyle Libre 3 Plus, highlighting their features, accuracy, and costs.
Expert opinion: Why is a CGM helpful?
According to Rachel Stahl, a registered dietitian and diabetes care and education specialist (DCES) at New York-Presbyterian and Weill Cornell Medicine, continuous glucose monitoring can offer helpful insights into the things affecting your glucose levels:
“(Users) can learn a lot about the impact of lifestyle on glucose values, such as food intake, amount and quality of sleep, or type of exercise. That can be very eye-opening for the patient and motivate them to change behavior to improve glucose values,”
| Dexcom G7 | Dexcom G7 15 Day | FreeStyle Libre 3 Plus | |
|---|---|---|---|
| Approved age | 2 years and older | 18 years and older | 2 years and older |
| Sensor wear duration | 10 days (+ 12 hours grace period) | 15 days (+ 12 hours grace period) | 15 days |
| Warm-up time | 30 minutes | 60 minutes | 60 Minutes |
| MARD (accuracy—the lower the number, the better) | 8.2% to 9.1% | 8.2% to 9.1% | 8.2% |
| Reading frequency | every 5 minutes | every 5 minutes | every 1 minute |
| Connectivity | • smartphone iOS and android • smartwatch • Dexcom G7 receiver • digital health apps | • smartphone iOS and android • smartwatch • Dexcom G7 receiver • digital health apps | • smartphone iOS and android • smartwatch • LibreLinkUp mobile app • LibreView |
| Alerts | predictive and customizable | predictive and customizable | customizable |
| Insulin pump integration | Tandem, Omnipod 5, iLet | Tandem, Omnipod 5, iLet | Tandem, Omnipod 5, iLet, twiist |
| Water resistance | 2.4 meters (m) up to 24 hours | 2.4 m up to 24 hours | 1 m for 30 minutes |
| Cost | typically $20 or less per month (with insurance) • pharmacy savings card available | • typically $20 or less per month (with insurance) • pharmacy savings card available | • typically $0 to $20 per month (with insurance) • copay card available |
| Placement on body | • back of upper arm or abdomen (ages 2+) • upper buttocks (ages 2 to 6) | back of upper arm | back of upper arm |
The Dexcom G7 and the new Dexcom G7 15 Day are Dexcom’s latest models, featuring several upgrades from the Dexcom G6 model.
- The Dexcom G7 is suitable for people ages 2 years and over.
- The G7 15 Day is suitable for people ages 18 years and over.
Both models offer the following benefits:
10- or 15-day sensor
Both Dexcom G7 models come with a combined sensor and transmitter that you apply to your body by pushing a button on an auto-applicator.
The sensor is FDA approved for wear on the back of your arm or abdomen. Pregnant people should avoid wearing it on the abdomen. For children ages 2 to 6 years, the Dexcom G7 can be worn on the upper buttocks.
The Dexcom G7’s sensor lasts for 10 days and the G7 15’s lasts for 15 days before needing to be replaced. They both have a 12 hour grace period in which to change the sensor. After this time, the sensor automatically shuts off. Watch this video that demonstrates how to change the sensor.
The sensor is water-resistant, so it can be worn in the shower or while swimming to depths of 2.4 m.
Data delivery
Glucose readings are automatically sent to a compatible smartphone enabled with the Dexcom G7 app or Dexcom receiver every 5 minutes. This requires bluetooth to be enabled and the app to be running.
Alerts and alarms
Users can set programmable alerts for high and low ranges. A mandatory “urgent low soon” alert predicts if glucose will drop to 55 mg/dL within 20 minutes.
Connectivity
You can download the Dexcom G7 app to receive readings to your phone. Make sure you do this in the country where you bought the CGM, as you won’t be able to download it from abroad.
You can also buy a dedicated, lightweight G7 receiver to use alongside or as an alternative to a smartphone.
Integration with automatic insulin delivery (AID) systems
The Dexcom G7 and G7 15 Day integrates with AID pumps like the Tandem t:slim X2, Omnipod 5, and Beta Bionics iLet Bionic Pancreas, to create “closed-loop” systems that automatically adjust insulin delivery.
Abbott’s FreeStyle Libre 3 Plus is their latest innovation, offering real-time glucose readings and extended wear. It offers the following benefits:
Small 15-day sensor
The Libre 3 Plus sensor is the size of two stacked pennies, which is noticeably smaller than the Dexcom models. You apply it to the back of the arm by pushing down on an auto-applicator. The sensor lasts for 15 days before needing to be replaced.
It is FDA approved to be worn on the back of the arm only.
Watch this video to learn how to apply and remove the FreeStyle Libre 3 Plus sensor.
Data delivery
This model streams readings directly to the Libre app or receiver every minute, providing real-time insights into your blood glucose.
Alerts and alarms
The FreeStyle Libre 3 Plus allows you to customize your alerts by setting personalized thresholds for low and high glucose. There is an urgent low alarm that’s triggered when your glucose drops to 55 mg/dL and this alarm can’t be turned off. You’ll also hear an alarm when the sensor loses connection with your phone or receiver.
Connectivity
The FreeStyle Libre 3 system provides real-time glucose readings that can be viewed on a smartphone via the Libre app. The LibreLinkUp app allows approved family and friends to receive your real-time glucose readings, which is ideal for parents and caregivers.
The LibreView app allows healthcare professionals to view your glucose data so they can spot patterns that may inform your treatment.
Integration with AID systems
The FreeStyle Libre3 Plus integrates with several AID systems, such as the Tandem t:slim, Beta Bionics iLet Bionic Pancreas, and the mylife Loop system.
If you’re looking to connect with other people with diabetes, resources like Healthline’s Bezzy T2D offer an online safe space for community, peer and expert guidance, and support.
The standard measure of CGM performance is the mean absolute relative difference (MARD). With this measure, the lower the number, the better the accuracy.
Clinical data for the Dexcom G7 showed a MARD of 8.2% when placed on the arm and 9.1% when placed on the abdomen.
The FreeStyle Libre 3 plus has a similar MARD of 8.2% for adults and 8.1% for children.
The total cost of a CGM depends on the type of insurance coverage you have.
Start by checking your insurance plan’s coverage of CGM. Typically, both the Dexcom G7 models and the FreeStyle Libre 3 Plus are covered as a pharmacy benefit rather than durable medical equipment (DME).
If you have commercial insurance, you’ll typically pay $20 per month or less for either CGM.
Dexcom offer a free benefits check to determine your coverage. They also offer a pharmacy savings program for people who don’t have CGM coverage or who have a high copay. Once you have a prescription, you can use this coupon to save on Dexcom products.
There is a FreeStyle Libre copay card available for people with commercial insurance or those without insurance.
If your doctor recommends a CGM, they can help you understand your options and potential costs.
The Dexcom G7, G7 15 Day, and FreeStyle Libre 3 Plus present significant benefits for glucose management, but come with specific pros and cons for you to weigh up.
If you prefer a smaller, more discrete option, the FreeStyle Libre 3 Plus may be right for you. If you’d like flexibility on where to place your CGM, the Dexcom G7 offers that.
Each model offers connectivity with apps, smart devices, and insulin delivery systems. They are also covered by most commercial insurance plans.
Talk with your healthcare professional to determine the best option for you.
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