Continuous glucose monitors (CGMs) have reshaped how people with diabetes manage their health by offering real-time insights, trend data, and the ability to make faster, more informed decisions. Two of the most widely used systems are the Dexcom G7 and the FreeStyle Libre 3 Plus. A third CGM used to track glucose is the implantable Eversense 365 which won’t explore here. While both devices provide real-time data, their smartphone apps, alarms, features, and wearability are notably different. This article will layout everything you need to know to help decide which system is right for you!

Both the Dexcom G7 and Libre 3 Plus are worn externally and applied with disposable applicators. They are used by people with type 1 and type 2 diabetes to measure glucose through interstitial fluid, providing continuous data that helps track trends, identify how food affects glucose, supports insulin dosing decisions, and for some, connect to insulin pumps to automate insulin delivery.

Dexcom G7 comes in two versions: a 10-day sensor and a 15-day sensor. Both include an additional 12-hour grace period at the end of their wear cycle, extending them to 10.5 and 15.5 days respectively. The Libre 3 Plus lasts 15 days with no additional grace period. Both sensors are approved for ages 2 and older, but the G7 15 Day is currently only approved for ages 18 and older.

In terms of reading frequency, the Libre 3 Plus measures glucose levels every minutes, while the Dexcom G7 does so every 5 minutes. This means Libre could alert users to a low or high up to 5x faster than Dexcom. While readings populate more often on the Libre 3 Plus, connected insulin pumps for both CGMs adjust insulin delivery every 5 minutes.

Warm-up time also differs between the two. The Dexcom G7 10-day has a 30-minute warm-up period, while the 15-day version requires 60 minutes. The G7’s warm-up period begins as soon as the sensor is applied, regardless of whether it has been connected to the app. This allows users to overlap sensors, meaning you can apply a new sensor and let it warm up while the previous one is still active and seamlessly transition between the two without missing a reading.

The Libre 3 Plus has a 60-minute warm-up that only begins once the sensor is connected to a receiver, smartphone app or insulin pump. Sensor overlapping is not possible with the Libre 3 Plus.

CGM accuracy is measured using Mean Absolute Relative Difference (MARD), where a lower percentage indicates better accuracy. The Libre 3 Plus has a MARD of 8.0%. The Dexcom G7 10-day has a MARD of 8.2%, and the 15-day version improved to 8.0% (the lower the MARD, the more accurate). Dexcom’s G7 15 Day sensor has an updated algorithm that brings stronger accuracy which we explored in our review of the Dexcom G7 15 Day.

It is worth noting that all CGMs measure glucose through interstitial fluid rather than directly from the blood, which means readings can lag behind actual blood glucose levels by 5 to 10 minutes. Fingerstick readings may still be needed when symptoms do not match the displayed number.

The Dexcom G7 allows users to perform a fingerstick calibration to re-adjust sensor accuracy at any point. The Libre 3 Plus, on the other hand, requires fingerstick readings during the first 12 hours of sensor wear for insulin dosing, and does not support user calibration.

The Libre 3 Plus holds the title of smallest CGM on the market; roughly the size of two stacked pennies. The Dexcom G7 is about the size of two quarters. Both sensors are approved to be worn on the back of the upper arm. The G7 is also approved for the upper buttocks for children ages 2 to 6.

Dexcom G7 includes an overpatch in the packaging and Dexcom requires users to wear it. With the overpatch in place, the G7 occupies much more surface area on the arm and can collect dirt along the edges over the course of wear which is not aesthetically pleasing. The Libre 3 Plus doesn’t include an overpatch. It also collects grime under its adhesive, but it is less noticeable. Both sensors are water-resistant and suitable for showering, swimming, and exercise.

Both sensors connect to smartphone apps on iOS and Android, and each offer optional standalone receivers. Both apps display key metrics including time in range (TIR), average glucose, and GMI, which is a digital estimate comparable to an A1C.

The Libre app provides much more detailed insights with daily pattern graphs showing when glucose tends go high or low and at which hours, and tools for identifying recurring trends over time. The Dexcom app's Trends tab covers the core metrics but offers less depth within the app itself. For more detailed analysis, Dexcom offers Clarity, a web-based platform where users and healthcare providers can review detailed glucose graphs and trend reports.

The Libre 3 Plus only connects with one device at a time, whether that is a phone, pump, or receiver. The Dexcom G7 connects with up to three devices simultaneously, including a direct connection to an Apple Watch.

Both CGMs have Apple Watch apps, but only the G7 is capable of connecting directly to the watch without routing through a phone. This Direct-to-Apple Watch feature does not support the ability to share glucose readings over cellular via Dexcom Follow.

Both sensors allows users to customize high and low glucose alerts that can be silenced for up to six hours. However, both include a fixed urgent low alert that triggers at 55 mg/dL. This alert cannot be adjusted on either system.

The Dexcom G7 includes several additional alert capabilities. It features an Urgent Low Soon alert, which can predict and notify users up to 20 minutes before glucose is expected to drop below 55 mg/dL. This is a powerful feature that can get can help users get ahead of lows sooner. The Libre 3 Plus sends an urgent low alert only once glucose has dropped below that threshold.

The G7 also includes a Delay First Alert feature, which lets users set a threshold and a time window so that brief excursions that self-correct within the set timeframe do not trigger a notification. For example, I have my threshold set to 190 mg/dl for 30 minutes. If my levels go above 190 mg/dl for 15 minutes, then drops back drown—no alarm will sound.

Additionally, the G7 supports rate-of-change alerts for rapidly rising or falling glucose, as well as customizable vibration settings. These features are not available on the Libre 3 Plus.

Both CGM platforms have incorporated AI-powered food logging tools. The Libre 3 Plus app has Libre Assist. Users can take a photo of a meal or type in a description and the app will predict the expected glucose impact, categorizing it as minor, moderate, or high. It also provides tips on food choices, preparation methods, and eating order to help slow down glucose absorption. A few hours after the meal, users can return to the app for a post-meal analysis that shows the actual glucose impact.

Dexcom's food logging feature works at a more basic level. Users take a photo of their meal and the app automatically labels the food and logs it. A few hours later, users can view a graph showing how their glucose responded to the meal. It offers less predictive guidance than Libre Assist but provides useful meal-to-glucose context.

Both CGMs support data sharing with healthcare providers and family members or caregivers, which can be especially important for monitoring lows in real time.

The Libre ecosystem includes LibreView, a web-based reporting platform, and LibreLinkUp, an app that allows followers to view readings and receive alerts.

The Dexcom ecosystem includes Clarity (both in-app and web-based) for advanced data viewing and Dexcom Follow app for sharing levels and alarms with others. It is worth noting that internet connectivity is required for data sharing on both platforms when using a smartphone.

The Dexcom G7 integrates with Apple Health and Siri, enabling voice-activated glucose checks. It also works with a range of third-party display devices such as the Sugar Dash and Glowcose. This CGM can be connected to different devices while it’s connected to a pump.

The Libre 3 Plus is compatible with third-party devices when connected to a smartphone. When connected to a pump, it loses access to third-party display options since it can only connect to one device at a time. In some cases, these devices can grab glucose data from a connected pump’s share features.

As for pump compatibility, the Libre 3 Plus works with the Beta Bionics iLet, t:slim X2, twiist, and is in a limited market release with Omnipod 5. Integration with the Tandem Mobi is also planned. Note that when connected to a pump, sharing through LibreLinkUp is not available and readings must be shared through the pump's own platform instead.

The Dexcom G7 10-day works with Omnipod 5, Beta Bionics iLet, t:slim X2, and Mobi. The 15-day version is currently compatible with Omnipod 5, t:slim X2, and iLet, with Mobi support expected soon.

Both companies are actively working on next-generation technology. Abbott is developing a dual glucose-ketone sensor, which could help detect elevated ketone levels and potentially identify early risk for diabetic ketoacidosis (DKA), a serious and potentially life-threatening condition.

Dexcom is also exploring multi-analyte sensing, including ketones. The company has shared early details about the Dexcom G8, which is expected to be 50% smaller than current models with improved accuracy, better connectivity, and multi-analyte capabilities.

Disclaimer: Diabetech content is not medical advice—it’s for educational purposes only. Always consult with a healthcare team before making changes to your treatment.