Freestyle Libre vs Dexcom: Which Continuous Glucose Monitor Is More Accurate in 2025?

If you’re living with diabetes and trying to decide between Freestyle Libre and Dexcom, you’re probably wondering which continuous glucose monitor (CGM) delivers the most reliable readings. After all, accurate blood sugar data isn’t just about numbers on a screen—it’s about making confident decisions that directly impact your health every single day.

In 2025, both Freestyle Libre 3 and Dexcom G7 represent the cutting edge of CGM technology, offering impressive accuracy metrics and advanced features. But here’s the thing: choosing between them isn’t as simple as picking the device with the lowest MARD value. Real-world performance, sensor reliability, and how these devices fit into your lifestyle matter just as much as the technical specs.

This comprehensive comparison dives deep into the latest clinical data, FDA clearances, and real-world studies to help you understand which CGM might work best for your diabetes management. We’ll break down accuracy across different glucose ranges, explore sensor lifespan and calibration needs, and look at what actual users experience day-to-day.

• Both devices deliver excellent accuracy—Freestyle Libre 3 and Dexcom G7 both achieve MARD values between 8.2% and 12%, with performance varying by glycemic range and individual factors
• Dexcom G7 now offers extended wear—The recently FDA-cleared 15-day sensor matches Freestyle Libre’s 14-day duration while maintaining accuracy throughout the extended wear period
• Factory calibration simplifies both systems—Neither device requires fingerstick calibration, making diabetes management technology more convenient than ever before
• Hypoglycemia detection has improved significantly—While accuracy tends to be lower in hypoglycemic ranges for both devices, recent models show substantial improvements, with some studies reporting 97% of results within ±15 mg/dL
• Real-world hospital studies validate clinical use—Research from inpatient settings demonstrates both CGMs perform adequately for clinical decision-making, though with some variation in challenging scenarios
• Sensor reliability differences exist—User satisfaction remains high for both brands, but sensor failure rates, comfort during wear, and adhesive performance vary between the two systems
• Regulatory oversight continues to evolve—The 2025 Washington State Health Technology Assessment reports 4 Class 1 recalls for CGM systems in US markets, emphasizing the importance of staying current with device updates

Before we dive into the head-to-head comparison, let’s talk about how CGM accuracy is actually measured. The gold standard metric in diabetes management technology is called Mean Absolute Relative Difference, or MARD for short.

Think of MARD as a percentage that tells you how much a CGM reading differs from a laboratory-grade blood glucose measurement. For example, if a device has a MARD of 10%, it means the sensor readings are typically within 10% of the actual blood glucose value. Lower MARD values indicate better accuracy—a device with 8% MARD is more accurate than one with 12% MARD.

Why MARD Matters for Your Daily Diabetes Management

Abbott’s Freestyle Libre system has become incredibly popular since its introduction, largely because it brought factory-calibrated CGM to the mainstream market. The latest iterations—Libre 3 and Libre 2 Plus—represent significant improvements over earlier models.

Freestyle Libre 3 Accuracy Data

Clinical studies from 2025 show the Freestyle Libre 3 achieves MARD values ranging from 8.2% to 11.8% depending on the study population and testing conditions. This represents a substantial improvement over the original Libre system and puts it squarely in the “high accuracy” category for flash glucose monitoring technology.

What makes these numbers impressive is that Libre 3 maintains this accuracy throughout its entire 14-day sensor lifespan without requiring any fingerstick calibration. The factory calibration process happens before the sensor ever reaches your arm, which means less hassle for you and more consistent performance.

Freestyle Libre 2 Plus Improvements

The Libre 2 Plus shows similar accuracy improvements, with enhanced algorithm performance that better handles rapid glucose changes. This is particularly valuable during exercise or after meals when your glucose levels are shifting quickly.

Real-Time Monitoring and Alerts

Unlike the original Libre which required scanning, both Libre 3 and 2 Plus offer real-time glucose monitoring with customizable alerts. You’ll get notifications for high and low glucose levels, helping you catch problems before they become serious. This shift to continuous real-time data transmission brings the Libre line into direct competition with Dexcom’s alert capabilities.

Pregnancy Safety Considerations

For pregnant individuals with diabetes, accuracy becomes even more critical. Studies on CGM use in pregnancy report Freestyle Libre demonstrates a MARD of approximately 11.8% in pregnant populations, which falls within acceptable ranges for gestational diabetes management. However, healthcare providers typically recommend more frequent traditional blood glucose monitoring during pregnancy to validate CGM readings.

Sensor Wear Duration and Comfort

Dexcom has long been recognized as a leader in continuous glucose monitoring, and the G7 system represents the company’s most advanced technology yet. With the recent FDA clearance of a 15-day sensor version, Dexcom has addressed one of the key advantages Libre held in sensor longevity.

Dexcom G7 Accuracy Performance

The Dexcom G7 demonstrates MARD values between 8.2% and 10.3% in most clinical studies, with some research suggesting slightly better overall accuracy compared to previous Dexcom models. The G7’s smaller sensor size and improved algorithm contribute to consistent performance across a wide range of glucose values.

What’s particularly impressive about the G7’s accuracy is its consistency throughout the sensor wear period. Unlike some older CGM systems that showed decreased accuracy toward the end of the sensor life, the G7 maintains reliable readings from day one through day ten—and now through day fifteen with the extended sensor.

The Game-Changing 15-Day Sensor

In early 2025, the FDA cleared Dexcom’s 15-day G7 sensor for adults with diabetes. This extended wear duration matches Freestyle Libre’s traditional advantage while maintaining the accuracy and alert features Dexcom users have come to expect. The longer sensor life means fewer sensor changes, reduced waste, and potentially lower overall costs for users.

Factory Calibration and Ease of Use

Like Freestyle Libre, Dexcom G7 is factory calibrated and doesn’t require fingerstick calibration. However, users can perform optional calibration if they notice their readings seem off—a feature that provides some flexibility for those who want additional assurance during critical situations.

Advanced

Alert Features Dexcom’s alert system is highly customizable, allowing you to set different thresholds for different times of day. The predictive alerts can warn you up to 20 minutes before you’re expected to reach a high or low threshold, giving you time to take action proactively. This predictive capability, combined with the ability to share your data with up to 10 followers in real-time, makes Dexcom particularly popular among parents of children with diabetes and individuals at higher risk for severe hypoglycemia.

Integration with Insulin Pumps

Dexcom CGM systems integrate with various insulin pump systems and automated insulin delivery systems, which can be a deciding factor for individuals using or considering insulin pump therapy. This interoperability supports more sophisticated diabetes management approaches, including hybrid closed-loop systems that automatically adjust insulin delivery based on CGM readings.

Now let’s get to the question you’re really asking: which CGM is actually more accurate? The answer is nuanced, but here’s what the data shows.

Clinical Trial Comparisons

A comprehensive 2025 comparison study evaluated Freestyle Libre 3, Dexcom G7, and other CGM systems side by side. The results showed that both devices achieve excellent accuracy, with Dexcom G7 showing a slight edge in overall MARD performance (8.2-10.3% vs 8.2-11.8% for Libre 3).

However—and this is important—this difference is relatively small in practical terms. Both devices fall well within the accuracy ranges needed for effective diabetes management and meet FDA standards for continuous glucose monitoring devices.

Real-World Hospital Performance

A particularly revealing study examined real-world CGM performance in hospital settings. In this challenging environment with critically ill patients, the research found Freestyle Libre showed a MARD of 11.8% while Dexcom demonstrated 14.4% MARD in the inpatient setting.

Interestingly, this reverses the typical pattern seen in outpatient studies. Why the difference? Hospital patients often have more complex medical situations, different skin conditions from illness, and rapidly changing glucose levels that challenge any CGM system. The takeaway here is that CGM accuracy can vary based on the context and patient population.

Sensor Reliability and Failure Rates

Beyond raw accuracy numbers, sensor reliability matters tremendously. There’s nothing more frustrating than a sensor that fails early or gives inconsistent readings. Research on CGM precision and reliability shows both systems have improved significantly, but users report some differences in sensor failure rates and comfort during extended wear.

Dexcom users occasionally report sensor failures in the first 24 hours, while Libre users sometimes experience adhesive issues that can cause premature sensor loss. Both companies have improved their products’ reliability over time, but individual experiences vary widely.

Here’s something many people don’t realize: CGM accuracy isn’t constant across all glucose levels. The performance of these devices changes depending on whether your blood sugar is low, normal, or high.

The Hypoglycemia Challenge

Detecting and alerting you to low blood sugar is arguably the most critical function of a CGM. Unfortunately, it’s also where most CGMs struggle the most. Both Freestyle Libre and Dexcom show reduced accuracy in hypoglycemic ranges (typically below 70 mg/dL), though recent models have improved significantly.

Clinical data shows that in hypoglycemic ranges, CGM readings may lag behind actual blood glucose values by several minutes, and the absolute difference between CGM and blood glucose can be more pronounced. However, some studies report that modern systems like Libre 3 achieve 97% of results within ±15 mg/dL even in lower glucose ranges—a substantial improvement over earlier technology.

The practical implication? If your CGM alerts you to a low, it’s wise to confirm with a fingerstick test before treating, especially if you don’t have symptoms or if the reading seems unexpected. This double-check approach helps prevent overtreating lows that might not be as severe as the CGM suggests.

Euglycemia: The Sweet Spot

Both Freestyle Libre and Dexcom perform best when glucose levels are in the normal range (roughly 70-180 mg/dL). This is where you’ll see MARD values at their lowest, and CGM readings typically match fingerstick values very closely. This excellent performance in the euglycemic range supports one of the primary goals of CGM use: maximizing time in range.

Hyperglycemia Performance

When glucose levels rise into hyperglycemic ranges (above 180-250 mg/dL), both CGM systems maintain good accuracy, though typically not quite as precise as in the normal range. The good news is that small variations in accuracy matter less clinically when glucose is high—whether your actual glucose is 280 or 300 mg/dL doesn’t change your immediate treatment plan the way a difference between 55 and 70 mg/dL would.

Clinical Implications for Time in Range

Accuracy metrics tell only part of the story. How a CGM performs in real life—day after day, through showers and workouts, sleeping and swimming—matters just as much as laboratory accuracy numbers.

Sensor Comfort and Wearability

The Freestyle Libre 3’s smaller sensor size gives it an edge in discreteness and comfort for many users. It’s less likely to catch on clothing and generally feels less obtrusive during extended wear. However, Dexcom G7 represents a significant size reduction from the previous G6 model, narrowing this comfort gap considerably.

Both sensors attach to the back of the upper arm, though some users find creative placement alternatives (with varying degrees of accuracy). The adhesive quality can make or break your experience—Freestyle Libre’s adhesive tends to be stronger, which reduces premature sensor loss but can be more challenging to remove. Dexcom’s adhesive is generally gentler but may require additional overwraps in hot, humid conditions or during intense exercise.

Ease of Application

Both systems have streamlined their applicators to make sensor insertion as painless as possible. Freestyle Libre’s one-button applicator is incredibly straightforward, while Dexcom G7’s all-in-one sensor and transmitter design simplifies the process compared to earlier Dexcom models.

App Experience and Data Sharing

The smartphone apps for both systems have evolved significantly. Freestyle Libre’s LibreLink app provides clear glucose trends and statistics, with a simple interface that works well for users who prefer straightforward data presentation. Dexcom’s app offers more detailed analytics and customization options, including the highly valued “Follow” feature that allows caregivers or loved ones to monitor your glucose remotely.

Both apps integrate with compatible smartwatches, letting you check your glucose with a quick glance at your wrist. This convenience factor shouldn’t be underestimated—the easier it is to check your glucose, the more likely you are to stay engaged with your diabetes management.

Sensor Failure Experiences

Both manufacturers have good customer service records for replacing sensors that fail prematurely. Anecdotal reports suggest Dexcom experiences slightly higher early sensor failure rates (in the first 24-48 hours), while Freestyle Libre sensors occasionally fail in the final days of the wear period. However, both companies have robust replacement policies, so failed sensors typically don’t become a financial burden.

The regulatory landscape for continuous glucose monitors continues to evolve, with implications for device accuracy and user trust. Understanding recent FDA actions helps put CGM performance in context.

Recent FDA Clearances

The most significant 2025 regulatory development was the FDA clearance of Dexcom’s 15-day G7 sensor. This approval required Dexcom to demonstrate that accuracy remains consistent throughout the extended wear period, providing users with confidence that day-15 readings are as reliable as day-1 readings.

Both Freestyle Libre and Dexcom systems have received FDA clearances that allow them to be used for diabetes treatment decisions without confirmatory fingerstick tests (often called “non-adjunctive” use). This regulatory classification reflects the high accuracy these devices have achieved and the FDA’s confidence in their clinical reliability.

Safety Monitoring and Recalls

The 2025 Washington State Health Technology Assessment comprehensively reviewed CGM safety, noting that there have been 4 Class 1 recalls for CGM systems in US markets. Class 1 recalls indicate situations where device use might cause serious adverse health consequences, though actual harm from these recalls has been limited.

These recalls highlight the importance of keeping your CGM device and app updated with the latest software and following manufacturer guidance carefully. Most recall situations are resolved through software updates rather than device returns, emphasizing why staying current with app updates matters for both accuracy and safety.

Ongoing Accuracy Standards

After examining all the clinical data, real-world studies, and user experiences, here’s the bottom line: both Freestyle Libre 3 and Dexcom G7 are excellent continuous glucose monitors with impressive accuracy that can transform your diabetes management. Dexcom G7 holds a slight edge in overall accuracy metrics, while Freestyle Libre 3 offers a more compact sensor design and has traditionally provided longer wear duration (though Dexcom’s new 15-day sensor levels that playing field).

The truth is, choosing between them often comes down to factors beyond pure accuracy numbers. Consider what matters most to you: Do you value the predictive alerts and extensive data sharing capabilities that Dexcom offers? Or do you prefer Freestyle Libre’s compact sensor and streamlined approach? Does your insurance cover one system better than the other? Do you need integration with an insulin pump system?

Both devices have achieved non-adjunctive FDA clearance, meaning they’re accurate enough to make diabetes treatment decisions without confirmatory fingersticks. Both offer factory calibration, real-time alerts, and smartphone connectivity. Both provide the accuracy needed to improve your time in range and overall glycemic control.

If you’re still unsure which system might work better for you, talk with your healthcare provider about trying one system for a few months. Many people find that living with a CGM for a while reveals preferences they didn’t anticipate from reading specifications alone. Some insurance plans and manufacturers offer trial programs that let you experience the technology before committing long-term.

Whichever system you choose, you’ll be joining millions of people with diabetes who have discovered that continuous glucose monitoring—with its minute-by-minute insights, trend arrows, and predictive alerts—makes diabetes management feel less like guesswork and more like informed decision-making. And that might be the most important accuracy improvement of all.

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