FreeStyle Libre 3 Plus & Dexcom G7 15 Day: an in-depth comparison

Both systems offer customizable glucose alerts and allow users to share glucose readings and trends remotely with designated followers, such as family members or caregivers. They differ in age indications, reading frequency, alert features, device connectivity, and compatibility with insulin delivery systems.

This comparison highlights key features to consider when selecting, initiating, and providing training on CGM use. As a device-agnostic resource, danatech emphasizes that the best CGM is the one that meets the individual’s needs, preferences, lifestyle, and coverage considerations. Use this comparison to support a person-centered approach to CGM selection and use:

Both devices offer up to 15 days of indicated sensor wear. The Dexcom G7 15 Day includes an additional 12-hour grace period after the 15-day session, allowing flexibility in timing a sensor change. Both CGMs have a 60-minute warm-up before glucose readings become available. Wear the overpatch supplied with the Dexcom sensor.^{1, 2, 24}

When to use a blood glucose meter

For use with an automated insulin delivery (AID) system, follow that system’s instructions for sensor start-up, treatment decisions, and glucose-monitoring interruptions.

MARD (mean absolute relative difference) summarizes the average percentage difference between CGM readings and reference glucose measurements in a study. A lower MARD indicates closer average agreement under that study’s conditions. The reported adult-study MARD is 8.0% for Dexcom G7 15 Day and 8.2% for FreeStyle Libre 3 Plus. These results come from separate studies and do not establish that one device is more accurate than the other for an individual.^{2, 8}

The Libre 3 Plus updates glucose readings every minute; the G7 15 Day updates readings every five minutes. The clinical importance of this difference depends on how the person uses glucose trends, alerts, and connected devices.

Scope: The alert comparisons below describe the Dexcom G7 and Libre smartphone apps. They should not be applied to dedicated receivers/readers or connected AID apps, which have their own instructions and alert behavior.

Required alerts and alarms

Both Dexcom G7 15 Day and FreeStyle Libre 3 Plus have required urgent-low alerts with a fixed 55 mg/dL threshold and certain technical or system alerts that cannot be disabled. Both systems offer options to temporarily silence audible glucose alerts for up to six hours. However, the systems differ in which alerts can be silenced and how notifications are delivered.^{1, 2}

Selected alerts and alarms that cannot be turned off

Alert names differ between systems. These are examples, not a complete list of technical alerts.^{1, 2}

Alerts and alarms that can be turned off

How smartphone silent modes affect sound and vibration

Sources for app alerts and silent modes121516

CGM compatibility with automated insulin delivery systems is an important consideration for people using or considering insulin pump therapy. Compatibility depends on the exact CGM model, insulin delivery device, software or firmware version, and commercial availability. Confirm the current manufacturer compatibility information before prescribing or switching sensors. The sensor’s age indication does not establish eligibility for every connected AID system; check the complete system’s age and other eligibility requirements.^{9, 12}

Verify current AID compatibility: Dexcom integrations and compatibility and Abbott FreeStyle Libre pump compatibility

Compatibility sources910111213

Both Dexcom G7 15 Day and FreeStyle Libre 3 Plus support glucose alerts on a compatible Apple Watch, but they differ in how alerts are transmitted. Dexcom G7 15 Day supports direct sensor-to-watch connectivity, allowing glucose readings and alerts to continue when the iPhone is not nearby. FreeStyle Libre 3 Plus uses the Libre app for Watch, which receives glucose information through the iPhone. The iPhone must remain within range of both the sensor and watch. Do not use Libre watch readings for treatment decisions; use the Libre phone app.^{1, 14}

Alert settings are managed through the respective smartphone apps. After changing Dexcom settings on the iPhone, open the Dexcom watch app while the phone is nearby to synchronize the changes. Libre 3 Plus notifications follow the iPhone’s Apple Watch notification-mirroring settings. Sound and vibration behavior may also depend on Apple Watch settings. Users should verify how glucose alerts are delivered on their watch, particularly when using silent modes or leaving their smartphone behind. Libre notifications may appear on the iPhone or Apple Watch rather than both.^{1, 14}

Apple Watch alert considerations

There is no single CGM that is the best fit for everyone. Selection may depend on age indication, insulin delivery system compatibility, preferred display device, alerts, data sharing, adhesive tolerance, training needs, and insurance coverage. Incorporating these considerations into shared decision-making can help the person choose technology that fits their daily life and diabetes management goals.

1. Understanding alerts and alarms is essential for safe CGM use.Both systems have required glucose and technical alerts that cannot be disabled, although some can be temporarily silenced. Differences in silent modes, vibration, and alert customization should be addressed during training.
2. CGM selection should be individualized.Device features, insulin delivery needs, lifestyle, preferences, training requirements, and insurance coverage should guide shared decision-making. No single CGM is the best choice for everyone.
3. CGM features and connectivity are important considerations when selecting a device.Both systems offer remote data sharing, Apple Watch connectivity, and integration with compatible automated insulin delivery (AID) systems. Differences in how glucose information is transmitted to the Apple Watch, along with AID compatibility and other connectivity features, can influence device selection based on individual needs and preferences.