A continuous glucose monitor (CGM) sits on or under your skin, samples interstitial fluid every minute or two, and pushes a reading to your phone so you can see exactly how food, stress, sleep, and exercise move your numbers. For people with type 1 or type 2 diabetes the data turns guesswork into a feedback loop, and for prediabetes or metabolic curious users it surfaces patterns no fasting test would catch.
This guide focuses on five sensors that consistently rank well for accuracy, app reliability, and real world wear: Dexcom G7, Abbott FreeStyle Libre 3, the FreeStyle Libre 3 Plus, Eversense E3, and Medtronic Guardian Connect. We weighed published MARD figures, sensor session length, alert customization, integration with insulin pumps and smartwatches, and the friction of replacing a sensor every week or two.
Medical disclaimer: this article is informational only and does not replace advice from a licensed clinician. Talk to your endocrinologist or primary care provider before starting, changing, or stopping any glucose monitoring or diabetes treatment plan.
Comparison Table
| Sensor | Wear Time | Reported MARD | Calibration | Best For |
|---|---|---|---|---|
| Dexcom G7 | 10 days + 12h grace | 8.2% | None | Pump integration |
| FreeStyle Libre 3 | 14 days | 7.9% | None | Long wear value |
| FreeStyle Libre 3 Plus | 15 days | 7.8% | None | iOS and Android share |
| Eversense E3 | 180 days | 8.5% | 1 to 2 per day | Implant preference |
| Medtronic Guardian Connect | 7 days | 8.7% | 2 per day | MiniMed pump users |
Dexcom G7 - Smallest All In One Wearable
Verdict: the easiest CGM to recommend if you want pump compatibility and a quick warmup.
The Dexcom G7 dropped the separate transmitter that defined the G6, so the whole sensor and electronics sit in one low profile puck about the size of three stacked nickels. Application uses a single button inserter and the 30 minute warmup is the fastest on the market right now. Readings appear on iPhone, Android, Apple Watch Ultra, and Wear OS, and the system integrates directly with Tandem t:slim X2 and Omnipod 5 pumps for automated insulin dosing.
In a 2024 study published in Diabetes Technology and Therapeutics the G7 logged a MARD of 8.2 percent in adults and 8.1 percent in children, both strong results without any finger stick calibration. Predictive low and high alerts, urgent low soon warnings, and customizable schedules sit inside the Dexcom G7 app, and the new Stelo brand uses the same hardware for non insulin users. Pharmacy pricing through GoodRx hovers in the same range as Libre 3, and Medicare Part B covers the sensors when your provider files the right codes.
Abbott FreeStyle Libre 3 - Longest Mainstream Wear Time
Verdict: the best value sensor when 14 day sessions and a slim profile matter more than pump pairing.
FreeStyle Libre 3 is the smallest CGM on the market today, roughly the size of two stacked pennies, and it sticks to the back of the upper arm with a one piece applicator. Readings stream every minute over Bluetooth to the LibreLink app on iOS and Android, and LibreLinkUp lets up to 20 followers see the data in real time. There is no scanning step like the original Libre, no separate transmitter, and no factory calibration interruptions.
Abbott reports an overall MARD of 7.9 percent in adult studies, which puts the Libre 3 in the same accuracy band as the Dexcom G7 and slightly ahead of Guardian Connect. Optional high and low alarms with custom thresholds make the system usable for people on basal insulin or those simply tracking glycemic response to meals. The newer Libre 3 Plus extends wear to 15 days and is the sensor Abbott uses for its Tandem and Sequel pump integrations.
Shop FreeStyle Libre 3 on Amazon
Eversense E3 - 180 Day Implantable Sensor
Verdict: the right pick if you would rather replace a sensor twice a year than every two weeks.
Eversense E3 is the only implanted CGM available in the United States. A clinician inserts the fluorescence based sensor just under the skin of the upper arm in a short office procedure, and a removable transmitter sits on top of the site, held by a daily disposable adhesive. The transmitter buzzes through clothing for low and high alerts, which some users prefer over phone notifications during meetings or while exercising.
The published MARD is 8.5 percent across the 180 day session, with required finger stick calibrations once or twice a day. Senseonics, the maker of Eversense, secured a 365 day version that is rolling out as supply expands, which would cut clinic visits in half. The trade off is the in office insertion and removal, plus the daily adhesive that some users find more visible than the slim Libre 3 patch.
Medtronic Guardian Connect - Best For MiniMed Pump Users
Verdict: choose Guardian Connect if you already use a Medtronic MiniMed 780G or plan to.
Medtronic Guardian Connect uses the Guardian Sensor 3 and a small rechargeable transmitter that talks to the Guardian Connect app over Bluetooth. The system is also the CGM that pairs with the MiniMed 780G hybrid closed loop pump in SmartGuard mode, automating basal and correction doses based on the sensor reading. For users committed to the Medtronic ecosystem this tight integration is the main reason to pick it.
Reported MARD lands at 8.7 percent across adult and pediatric studies, with two finger stick calibrations per day to keep the sensor on track. Predictive alerts give up to 60 minutes of warning before a projected low or high, and the CareLink platform produces detailed time in range reports your endocrinologist can pull during visits. Sensor sessions run seven days, so plan on more frequent inserter use than with the G7 or Libre 3.
Shop Medtronic Guardian Connect on Amazon
FreeStyle Libre 3 Plus - Extended Pump Ready Sensor
Verdict: the version of Libre to choose if you want 15 day wear and future pump pairing.
The Libre 3 Plus uses the same one piece form factor as the standard Libre 3 but extends wear time to 15 days and serves as the dedicated sensor for Abbott's automated insulin delivery partnerships. Reported MARD in the Plus pivotal study was 7.8 percent, a small but measurable improvement over the original Libre 3, and the warmup window stayed at 60 minutes. The smartphone app, LibreLinkUp sharing, and optional alarms carry over without changes.
If you are starting from scratch in 2026 and have a choice between Libre 3 and Libre 3 Plus, the Plus is the better long term pick because Abbott is steering its pump integration roadmap through that sensor. The standard Libre 3 remains a great option where Plus distribution is still rolling out or pharmacy stock is limited.
Shop FreeStyle Libre 3 Plus on Amazon
How To Choose The Right CGM
Match the sensor to how you actually use the data. If you are on multiple daily injections or an automated insulin pump, prioritize a system that pairs with your pump and pushes alerts to a smartwatch. Dexcom G7 covers Tandem and Omnipod, Libre 3 Plus covers Tandem and Sequel, and Guardian Connect locks into the MiniMed 780G. For non insulin users or anyone tracking metabolic patterns, wear time and app simplicity matter more, which puts Libre 3 and Dexcom Stelo near the top.
Skin tolerance is the other variable nobody talks about until a sensor falls off. Try overlay patches like Skin Tac or Simpatch from the start, rotate sites between arms, and check insurance coverage before paying retail. If the daily adhesive on Eversense bothers you, the 180 day insertion may not save the hassle you expect. Talk to your clinician about goals like time in range, hypoglycemia avoidance, or post meal insight so the device fits the plan rather than the other way around.
For deeper dives, see our continuous improvement certifications guide and our continuous release melatonin roundup. For how we score health wearables, read our methodology.
Frequently asked questions
Do I need a prescription to buy a continuous glucose monitor?+
In the United States most CGMs still require a prescription, although the FDA cleared the first over-the-counter sensor for adults without diabetes in 2024. Dexcom Stelo and the Abbott Lingo follow that path, while Dexcom G7, FreeStyle Libre 3, Eversense E3, and Medtronic Guardian Connect remain prescription devices. If you have diabetes, your endocrinologist or primary care provider can write the script and route it through pharmacy or durable medical equipment channels for insurance coverage.
How accurate are continuous glucose monitors compared to finger sticks?+
Modern CGMs report a mean absolute relative difference (MARD) of roughly 8 to 10 percent against laboratory reference values, which is close to many home blood glucose meters. Dexcom G7 and FreeStyle Libre 3 both publish MARD figures under 9 percent in adult studies. Finger sticks remain the standard when symptoms do not match the sensor reading, during rapid changes, or when calibrating implanted systems like Eversense E3.
How long does each sensor last on the body?+
Wear time varies a lot between brands. FreeStyle Libre 3 runs for 14 days, Dexcom G7 lasts 10 days plus a 12 hour grace period, Medtronic Guardian Connect uses a 7 day sensor, and the implanted Eversense E3 stays in place for 180 days before a clinician replaces it. Longer wear reduces sticker waste and pharmacy trips, but shorter sessions can mean fewer skin reactions for sensitive users.
Can I share my CGM data with my doctor or family?+
Yes, every system on this list offers cloud sharing through a partner app. Dexcom Follow, LibreLinkUp, Medtronic CareLink, and the Eversense companion app all let approved followers see live readings and trend arrows. Clinic portals like Dexcom Clarity and LibreView pull the same data for medication titration. Set sharing up during the initial sensor session so caregivers receive the urgent low and high alerts automatically.
Will insurance or Medicare cover a continuous glucose monitor?+
Medicare Part B covers therapeutic CGMs for people who use insulin or have a documented history of problematic hypoglycemia, and most private plans follow similar criteria. Coverage usually flows through pharmacy benefits for Dexcom G7 and Libre 3, while Medtronic and Eversense often route through durable medical equipment. Call your plan with the HCPCS code your prescriber uses so you know the copay before the first shipment lands.
Morgan Davis
Morgan Davis writes for The Tested Hub.