Continuous Glucose Monitor Review: Top CGM Devices Compared (2025)

Managing blood sugar effectively means having access to real-time data — and that is exactly what a continuous glucose monitor (CGM) delivers. Unlike traditional fingerstick meters that give you a single snapshot, a CGM tracks your glucose levels around the clock, alerting you to highs, lows, and trends before they become a problem.

But with several CGM devices now on the market — each with different features, costs, and prescription requirements — choosing the right one can feel overwhelming. This continuous glucose monitor review breaks down the leading devices, compares their strengths and weaknesses, and helps you figure out which option makes the most sense for your situation.

Whether you have Type 1 diabetes, Type 2 diabetes, or you are simply trying to better understand how food and lifestyle affect your blood sugar, this guide has you covered.

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What Is a Continuous Glucose Monitor and How Does It Work?

A CGM is a small wearable device that measures glucose levels in the interstitial fluid (the fluid surrounding your cells) rather than directly in the blood. It typically consists of three parts:

• **A small sensor** inserted just under the skin, usually on the arm or abdomen
• **A transmitter** that sends data wirelessly
• **A receiver or smartphone app** that displays your glucose readings in real time

Most modern CGMs take a reading every one to five minutes and display a trend arrow showing whether your glucose is rising, falling, or stable. Many devices also include customizable alerts that notify you when levels go above or below your target range.

This continuous stream of data is a major upgrade over checking glucose manually a few times a day. It helps you understand how meals, exercise, stress, and sleep all affect your blood sugar — insights that are hard to capture with a traditional meter alone. If you want to understand more about how glucose monitoring fits into a broader health strategy, our Blood Sugar Monitoring at Home: Complete Guide is a great place to start.

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Top CGM Devices Reviewed

1. Dexcom G7

The Dexcom G7 is widely regarded as one of the most accurate and user-friendly CGMs available in 2025. It is FDA-approved and does not require fingerstick calibration, making day-to-day use very convenient.

Key features:

• Wear time: 10 days per sensor
• Warm-up time: 30 minutes (significantly faster than previous generations)
• Integration: Works with Apple Health, Google Fit, and most insulin pumps
• Alerts: Fully customizable high/low alarms
• Sharing: Real-time data sharing with up to 10 followers

Accuracy: The G7 has a Mean Absolute Relative Difference (MARD) of around 8.2%, which is among the best in its class. MARD is the standard way CGM accuracy is measured — the lower the number, the closer readings are to a reference blood glucose value.

Cost: The Dexcom G7 requires a prescription. With insurance it can be very affordable, but out-of-pocket costs for sensors typically run $300–$400 per month without coverage.

Best for: People with Type 1 or Type 2 diabetes who want premium accuracy and seamless device integration.

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2. Abbott FreeStyle Libre 3

The FreeStyle Libre 3 is Abbott’s latest CGM and has become extremely popular for its combination of affordability, accuracy, and a remarkably slim sensor profile — about the size of two stacked pennies.

Key features:

• Wear time: 14 days per sensor
• Warm-up time: 60 minutes
• Reading method: Automatic every minute (no scanning required, unlike earlier Libre models)
• App: Data viewable directly on smartphone via Bluetooth
• Alerts: High and low glucose alerts included

Accuracy: The Libre 3 reports a MARD of approximately 7.9%, making it one of the most accurate CGMs currently on the market.

Cost: Generally more affordable than the Dexcom G7, particularly for people without insurance. Abbott also offers a savings program that can reduce sensor costs significantly.

Best for: People looking for an accurate, comfortable CGM at a lower price point, and those who prefer a longer sensor wear time.

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3. Medtronic Guardian 4

The Medtronic Guardian 4 is primarily designed for people who use Medtronic insulin pumps as part of a closed-loop (automated insulin delivery) system. It integrates tightly with the MiniMed 780G pump to adjust insulin delivery automatically.

Key features:

• Wear time: 7 days per sensor
• Warm-up time: 2 hours
• Calibration: Does not require fingerstick calibration in most circumstances
• Integration: Best in class with Medtronic pumps

Accuracy: MARD is reported around 8.7%, which is solid but slightly behind the G7 and Libre 3 in head-to-head data.

Cost: Requires a prescription and is generally used within the Medtronic ecosystem, so costs vary depending on your pump setup and insurance.

Best for: Current Medtronic pump users who want a fully integrated automated insulin delivery system.

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4. Stelo by Dexcom (OTC CGM)

Launched in 2024, Stelo is Dexcom’s over-the-counter CGM — no prescription required. It is designed for people with Type 2 diabetes who are not on insulin, or for health-conscious individuals who want to track glucose trends for general wellness.

Key features:

• Wear time: 15 days per sensor
• No prescription needed
• Pairs with the Stelo app
• Does not include urgent low glucose alerts (not designed for insulin users)

Cost: Approximately $99 per month for two sensors, making it one of the most accessible CGMs available.

Best for: People with Type 2 diabetes not on insulin, prediabetes, or anyone interested in metabolic health monitoring without needing a prescription.

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5. Abbott Lingo (OTC Wellness CGM)

Similar to Stelo, Abbott’s Lingo CGM is designed for the wellness market and does not require a prescription. It uses the same sensor hardware as the Libre platform and offers detailed insights into how lifestyle choices affect glucose levels.

Key features:

• Wear time: 14 days
• No prescription needed
• Designed around coaching and wellness goals rather than clinical diabetes management
• App-based with detailed trend analysis

Cost: Comparable to Stelo at roughly $49–$99 per two-week sensor.

Best for: Non-diabetics or prediabetics who want to optimize their metabolic health and learn how diet and exercise affect their glucose levels.

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CGM Accuracy: What the Numbers Actually Mean

One of the most common questions people have is how accurate CGMs really are compared to fingerstick meters. It is important to understand that CGMs measure interstitial fluid glucose, not blood glucose directly. This means there is always a slight physiological lag — usually 5 to 15 minutes — between what your CGM reads and what a fingerstick would show.

This lag matters most when your glucose is changing rapidly, such as right after a meal or during intense exercise. For this reason, some clinical situations still require a confirmatory fingerstick — particularly before making treatment decisions like adjusting insulin.

That said, modern CGMs have become accurate enough that the FDA has approved several of them as replacements for fingerstick testing in most situations. If you want a side-by-side look at how traditional meters compare, check out our review of the Best Glucose Meter for Accuracy: Top Picks 2025.

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Cost and Insurance Coverage: What to Expect

Cost is one of the biggest deciding factors when choosing a CGM, and the range is wide. Here is a general breakdown:

| Device | Prescription Required | Avg. Monthly Cost (No Insurance) |

|—|—|—|

| Dexcom G7 | Yes | $300–$400 |

| FreeStyle Libre 3 | Yes | $150–$250 |

| Medtronic Guardian 4 | Yes | Varies with pump |

| Stelo (Dexcom) | No | ~$99 |

| Abbott Lingo | No | ~$49–$99 |

Insurance coverage: Most major insurance plans, including Medicare, cover CGMs for people with Type 1 diabetes and for people with Type 2 diabetes who use insulin. Coverage for non-insulin users is expanding but still varies significantly by plan.

Manufacturer savings programs: Both Dexcom and Abbott offer patient assistance programs and savings cards that can meaningfully reduce out-of-pocket costs. Always check the manufacturer’s website before assuming you will pay full price.

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Who Should Use a CGM?

CGMs were originally developed for people with Type 1 diabetes, but their use has expanded considerably. Here is a practical breakdown of who benefits most:

Strong clinical case for CGM:

• People with Type 1 diabetes
• People with Type 2 diabetes on insulin therapy
• Anyone with frequent hypoglycemia (low blood sugar episodes)
• Pregnant women with gestational diabetes (under medical supervision)

Growing use cases:

• People with Type 2 diabetes not on insulin who want tighter glucose control
• Individuals with prediabetes wanting early intervention
• Athletes and biohackers optimizing metabolic performance
• People experimenting with diet changes — understanding [foods that spike blood sugar](https://www.affordablediabetesoptions.com/foods-that-spike-blood-sugar/) becomes much more tangible when you can watch the data in real time

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Practical Tips for Getting the Most Out of Your CGM

Once you have chosen a device, a few habits will help you get maximum value from it:

1. Calibrate when prompted — Some devices still benefit from occasional fingerstick checks, particularly during rapid glucose changes.

2. Wear your sensor correctly — Placement matters. Follow manufacturer instructions carefully for your specific body type.

3. Set alerts thoughtfully — Too many alerts leads to alert fatigue. Start with conservative thresholds and adjust based on your experience.

4. Review trend data regularly — The real power of a CGM is in the patterns, not just individual readings. Look at your data weekly to spot recurring highs or lows.

5. Share data with your care team — Most CGM apps allow you to share reports with your doctor, making appointments far more productive.

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Conclusion

The CGM market in 2025 offers something for almost every type of user — from clinical-grade devices for insulin-dependent diabetes to affordable over-the-counter options for general wellness monitoring. The Dexcom G7 and FreeStyle Libre 3 stand out as the top prescription options for accuracy and ease of use. For those who do not need or want a prescription, the Stelo and Abbott Lingo are genuinely exciting new entries that make CGM technology accessible to a much wider audience.

The best continuous glucose monitor for you ultimately depends on your health goals, budget, insurance situation, and whether you are managing an active diabetes diagnosis or simply looking to understand your metabolic health better. If you are new to blood sugar monitoring altogether, taking the time to understand normal blood sugar levels by age can give you a helpful baseline before you start interpreting CGM data.

As always, discuss any new monitoring approach with your healthcare provider — especially if you are adjusting medication or insulin based on the data you collect.

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Frequently Asked Questions