The best continuous glucose monitor depends on your insulin regimen, pump compatibility, and insurance. As of 2025, the three most commonly prescribed CGM systems in the U.S. are the Dexcom G7, the Abbott FreeStyle Libre 3 Plus, and the Medtronic Guardian 4. All three are factory-calibrated, smartphone-compatible, and cleared for people with type 1 or type 2 diabetes.
Why CGMs Matter for Diabetes Management
Continuous glucose monitors measure interstitial fluid glucose every 1 to 5 minutes through a small filament inserted under the skin. Instead of the handful of data points a fingerstick provides, a CGM generates roughly 288 to 1,440 readings per day. That density reveals trends, overnight lows, post-meal spikes, and the effect of exercise or stress in real time.
The ADA recommends CGM for most adults with type 1 diabetes and for many with type 2 diabetes on insulin. Studies have shown CGM use may improve A1C and increase time in range compared with fingerstick-only monitoring.
Top CGM Systems Compared
| Feature | Dexcom G7 | Libre 3 Plus | Medtronic Guardian 4 | Eversense E3/365 |
|---|---|---|---|---|
| Wear time | 10 days + 12-hr grace | 15 days | 7 days | 180-365 days |
| Warm-up | 30 min | 1 hr | 2 hr | 24 hr after insertion |
| Fingerstick calibration | Not required | Not required | Optional | 2x daily |
| Reading interval | 5 min | 1 min | 5 min | 5 min |
| Smartphone integration | iOS and Android | iOS and Android | iOS and Android | iOS and Android |
| Pump integration | Tandem, Omnipod 5, iLet | Tandem (select) | Medtronic 780G | None |
| Insertion | Self-insert adhesive | Self-insert adhesive | Self-insert + transmitter | In-office implant |
| Approximate MARD | ~8% | ~9% | ~10% | ~9% |
MARD (mean absolute relative difference) is the industry accuracy benchmark — lower is better. All four systems are FDA-cleared and, in most cases, cleared for insulin dosing without a confirming fingerstick.
Dexcom G7: The Top Choice for Many on Insulin
The Dexcom G7, cleared by the FDA in 2022, is one of the most widely used CGMs in the U.S. It’s 60 percent smaller than the G6, has a 30-minute warm-up, and displays readings every 5 minutes. The G7 integrates with the Tandem t:slim X2, Omnipod 5, and Beta Bionics iLet insulin delivery systems for automated insulin dosing.
The Dexcom app supports iPhone and Android, with optional Apple Watch direct connectivity. Sharing features allow up to 10 followers to view data in real time. Alarms for highs, lows, and urgent low-soon predictions are customizable.
FreeStyle Libre 3 Plus: Longest Wear, Smallest Sensor
Abbott’s Libre 3 Plus is the smallest CGM on the market (about the size of two stacked pennies) and lasts 15 days. It sends readings every minute to a smartphone, with optional alarms for highs and lows. Libre 2 Plus, which uses a separate reader or phone scanner, is also still available and often cheaper.
The Libre system historically undercut Dexcom on out-of-pocket cost and dominates the type 2, non-insulin-requiring market. The Libre 3 Plus is cleared for pediatric use starting at age 2.
Medtronic Guardian 4: Built for Medtronic Pumps
The Guardian 4 is designed to pair with the Medtronic MiniMed 780G automated insulin delivery system. It has a 7-day sensor wear time, a 2-hour warm-up, and optional calibration. For people committed to the Medtronic ecosystem, the integrated pump-CGM combo offers hands-free sensor-augmented pump therapy.
Guardian 4 standalone adoption (without the pump) is relatively uncommon because competitors offer longer wear time and similar accuracy.
Eversense: The Implantable Option
The Eversense E3 (6-month) and Eversense 365 (12-month) CGMs use a fluorescent sensor implanted in the upper arm by a clinician. A removable transmitter sits on the skin over the sensor and communicates with a smartphone. The implantable design appeals to people who dislike adhesive-based sensors or who have very active lifestyles.
Trade-offs include the need for an in-office insertion and removal, twice-daily fingerstick calibration, and higher upfront cost. Insurance coverage varies.
Cost and Insurance Coverage
CGM pricing depends heavily on insurance. With coverage, many users pay $30 to $75 per month through pharmacy benefits or durable medical equipment (DME) benefits. Without insurance, Dexcom G7 retails around $400 per month, Libre 3 Plus around $130 to $160 per month of supplies.
Medicare Part B covers therapeutic CGMs for beneficiaries on any insulin regimen and for those with problematic hypoglycemia. Most commercial insurers cover CGMs for type 1 and insulin-treated type 2 diabetes. Non-insulin coverage for type 2 has expanded but varies by plan.
Choosing the Right CGM
The right CGM for you depends on several factors:
- Insulin use. If you’re on a pump, choose a CGM that integrates with your pump brand.
- Smartphone. Make sure the device’s app supports your iPhone or Android model.
- Wear time. Longer is cheaper per day and less hassle.
- Sharing. If caregivers or partners need to follow your data, check sharing options.
- Insurance. Call your plan to verify coverage before starting.
- Skin sensitivity. Some adhesives work better for some people; Eversense may help if you react to patches.
Our diabetes treatment guide explains how CGMs fit into a broader management plan including medication and lifestyle.
CGMs for Prediabetes and Non-Diabetes Use
CGMs are increasingly popular for people with prediabetes or general metabolic curiosity, even outside FDA-labeled indications. In 2024, Dexcom and Abbott both launched over-the-counter CGMs (Stelo and Lingo) aimed at this market. They’re not intended for people on insulin but may help users identify how meals, sleep, and exercise affect glucose.
If you have prediabetes, a CGM can be an educational tool, though the evidence that short-term CGM use improves long-term A1C outside diabetes is still emerging.
Safety, Accuracy, and Limitations
CGMs measure interstitial fluid glucose, which lags plasma glucose by 5 to 15 minutes. During rapid glucose changes, CGM readings may lag. Severe dehydration, some medications (high-dose vitamin C, acetaminophen in some older sensors, hydroxyurea), and hemodialysis can affect accuracy.
The FDA’s CGM guidance notes that sensor readings should be confirmed with a fingerstick when they don’t match symptoms.
The Bottom Line
The best continuous glucose monitor depends on your diabetes type, pump compatibility, smartphone, and insurance coverage. Dexcom G7 leads on pump integration and is a strong choice for insulin users. FreeStyle Libre 3 Plus offers the longest wear time and smallest sensor. Medtronic Guardian 4 pairs with the MiniMed 780G pump. Eversense provides an implantable alternative. Talk with your endocrinologist or primary care clinician about which system matches your treatment plan and which your insurance covers.
