Dexcom CGM Explained
Dexcom G7 and Dexcom G7 15 Day vs. Libre 3 and Libre 3 Plus
Published: Dec. 1, 2025
Updated: Dec. 12, 2025
7 min read
The content in this article should not be taken as medical advice. Please consult with your healthcare provider regarding your individual health needs.
Technology has revolutionized diabetes management, giving people with diabetes new options that are easier, more accurate, and more advanced. This includes Continuous Glucose Monitoring (CGM) technology, which has empowered millions with diabetes to gain better control of their glucose levels and live happier and healthier lives.
But not all CGM systems are the same.
Dexcom G7 and Dexcom G7 15 Day CGM Systems make it possible to get accurate glucose readings without fingersticks.† Other devices such as FreeStyle Libre 3 and Libre 3 Plus can also provide a view into glucose levels without using a blood glucose meter. While Dexcom and FreeStyle Libre CGM Systems support continuous glucose monitoring and management for those living with diabetes, their features and benefits are not equal.
† If your glucose alerts and readings from Dexcom G7 do not match symptoms or expectations, use a blood glucose meter to make diabetes treatment decisions.
Compared with FreeStyle Libre 3, Dexcom G7 is more accurate,1 warms up faster,‡ and allows you to make treatment decisions in the first 11.5 hours of wear.2 In addition, Dexcom G7 is more affordable§,1 for most people.
In addition to affordability and faster treatment decisions, the new Dexcom G7 15 Day CGM System is more accurate1 and has the longest wear time available.||,¶,1
Since everyone experiences diabetes in their own way and no two people have the same needs, let’s compare Dexcom G7 CGM Systems with FreeStyle Libre 3 CGM Systems to explore which best fits your lifestyle and management goals.
What’s the difference between Dexcom G7 and Dexcom G7 15 Day and FreeStyle Libre 3 and Libre 3 Plus?
Both Dexcom G7 and FreeStyle Libre 3 CGM Systems provide glucose readings using a sensor worn on the body and send them to a display device, so you can view glucose levels on your compatible smartphone* in real time. Though there are some similarities between the two systems, they offer different glucose monitoring experiences.
See why Dexcom G7 and Dexcom G7 15 Day are the most powerful CGM systems1 from the most recommended CGM brand by patients and healthcare providers.3,4
Benefits of CGM | Dexcom G72 | Dexcom G7
15 Day5 | Abbott
FreeStyle
Libre 36 | Abbott FreeStyle Libre Libre 3 Plus7 |
The most accurate CGM1 | ✓ | |||
The most accurate CGM for children1 | ✓ | |||
Predictive urgent low soon alert | ✓ | ✓ | ||
Sensor warmup time | 30 minutes | 60 minutes | 60 minutes | 60 minutes |
Time before making insulin treatment decisions without fingersticks | 30 minutes | 60 minutes | 12 hours | 12 hours |
Most frequent out-of-pocket cost per month for most covered patients§,1 | $0 | $0 | $80 or more | $80 or more |
Wear time | 10.5 days (includes 12-hour grace period) | 15.5 Days (includes 12-hour grace period) | 14 days | 15 days |
Number of simultaneous Bluetooth connections (phone, smart watch,* receiver or AID system**) | 3 | 3 | 1 | 1 |
Available for integration with multiple insulin pumps and pens** | iLet Bionic Pancreas Lilly Tempo Insulin Pen Omnipod® 5 Tandem
Mobi System Tandem
t:slim X2™ insulin pump | iLet Bionic Pancreas Omnipod® 5 More coming soon | iLet Bionic Pancreas twiist™ Automated Insulin Delivery System | |
Ability to share glucose data†† while connected to an AID system | ✓ | ✓ | ||
Age indication | 2+ years | 18+ years | 4+ years | 2+ years |
Direct to
Apple Watch connectivity‡‡ | ✓ | ✓ |
1. Accuracy and Overall Effectiveness
Dexcom G7 has the best accuracy of any CGM available for pediatric users, and Dexcom G7 15 Day is the most accurate CGM for adults ages 18+.1 This means they have been shown to provide readings that are closest to clinical blood glucose readings.
One way the accuracy for a CGM system is measured is by mean absolute relative difference (MARD). The smaller the MARD number, the higher the accuracy. Dexcom G7 15 Day has a MARD of 8%5 while FreeStyle Libre 3 Plus has a MARD of 8.2%.7 This means Dexcom G7 15 Day is more accurate.
As the most accurate CGM for kids living with diabetes, Dexcom G7 delivers a MARD of 8.1% for children ages 6-17 years, and 7.7% for ages 2-6 years.2 Libre 3 and Libre 3 Plus have a published MARD of 9.4% and 8.2% respectively for ages 6-17 years and 11.5% and 9.7% respectively for ages 2-5.6,7
Using a Dexcom G7 CGM Systems is also clinically proven to lower A1C, increase the time you spend in your target glucose range, and reduce the amount of time you spend in a low/hypoglycemia range.8-14
If you’re not using a CGM, you’re likely used to using your blood glucose meter (BGM) to get your glucose readings. In that case, you should know
there is a difference between a BGM reading and your CGM readings and they may vary slightly when you compare the two.
2. Price and coverage
Clearly defining cost and coverage can be a moving target, as insurance providers and Medicare can change their policies and stipulations.
Dexcom is the most affordable CGM brand at pharmacy, and most patients pay $0 for Dexcom compared with $80 or more for FreeStyleLibre.§,1 With Dexcom CGM Systems, you get the best accuracy1 at a lower cost.
Both the Dexcom Savings Center page and FreeStyle Libre’s Cost and Coverage webpage offer savings vouchers depending on your health coverage.
3. Real-time continuous glucose monitoring
Both Dexcom G7 and FreeStyle Libre provide real-time glucose readings. Data is sent to a compatible smart device* or receiver for you to view your current glucose value. All systems also give you a trend arrow to show the direction your glucose is heading, and how quickly your glucose is rising or falling.
Dexcom G7 and Dexcom G7 15 Day send readings to your compatible smartphone every five minutes, and the receiver or smartphone can receive information up to 33 feet away.2,5 FreeStyle Libre 3 and Libre 3 Plus send readings every minute from up to 33 feet away.6,7
In addition, Dexcom G7 and FreeStyle Libre 3 CGM Systems all allow loved ones, parents, and caregivers to monitor glucose levels remotely with real-time updates.
The Dexcom Follow app enables up to 10 people to view glucose data and get alerts from your Dexcom G7 app on their own smart device.†† This is helpful especially for people who need extra support managing their glucose.
Libre LinkUp, FreeStyle Libre’s version of the Dexcom Follow app, enables up to 20 people to view glucose data and glucose alarms.
4. Painless sensor application and quick warm-up
Applying and changing the Dexcom G7 and FreeStyle Libre sensors is very similar. They all come with applicators that are pre-loaded with a sensor and are applied to the body, usually the back of the upper arm. This is usually painless for most Dexcom G7 users.§§,2,5
Dexcom G7 has the shortest warmup time of any CGM System, taking just up to 30 minutes from the moment the sensor is applied to your first reading.‡ That’s half the time of FreeStyle Libre 36 and FreeStyle Libre 3 Plus, which take 60 minutes.7 This means with Dexcom G7, kids living with diabetes and their parents can get their glucose readings and some extra peace of mind sooner.
Like Libre 3 and Libre 3 Plus, Dexcom G7 15 Day has a 60-minute warmup.5
5. Sensor wear, water resistance
Both Dexcom G7 and FreeStyle Libre 3 CGM Systems have discreet sensors about the size of a couple of stacked coins, with FreeStyle Libre 3 and 3 Plus being slightly smaller. Dexcom G7 sensors are more comfortable and discreet than Dexcom G6, at about 60% of the size. The small size and upper-arm wear location is comfortable and makes it easy to forget you’re even wearing it.1
The Dexcom G7 sensor can be worn for up to 10.5 days, while the FreeStyle Libre 3 and Libre 3 Plus sensors can be worn for up to 14 or 15 days, respectively.6,7 The new Dexcom G7 15 Day is the longest-lasting CGM system available with a 15.5-day wear time.§,||,1
Both Dexcom G7 CGM Systems have a bonus 12-hour grace period at the end of the 10- or 15-day session, giving you some added flexibility to change out the sensor when it’s most convenient for you.
Both Dexcom G7 sensors are waterproof in as much as 8 feet of water for up to 24 hours when properly installed.2,5 This means you can feel more confident wearing your sensor while you’re sweating, taking a long bath, or going for a swim. FreeStyle Libre 3 and Libre 3 Plus are only water-resistant up to 3.2 feet for 30 minutes or less.
6. Glucose alerts and alarms
Dexcom G7 and FreeStyle Libre CGM Systems all have alerts or alarms that can notify you when your glucose levels are high or low. However, the Dexcom G7 App has a wider range of customizable alerts designed to help you take action to help increase time in your target range and decrease highs and lows.8-14 These include:
- Urgent Low Soon Alert — The predictive Urgent Low Soon alert can warn you in advance (within 20 minutes) of a severe hypoglycemic event (55 mg/dL), which gives you time to take action before a low glucose event occurs.
FreeStyle Libre CGM Systems alert you when you reach high and low glucose thresholds, but not before. This may make it more challenging to anticipate the steps you need to take to avoid potentially serious lows.
- Delay 1st High Alert: Dexcom G7 and Dexcom G7 15 Day are the only CGM Systems with a Delay 1st High alert designed to reduce alert fatigue and insulin stacking.1 With it, you can delay your first high alert and avoid getting another alert long enough for the insulin to work. You can also customize when you’d like to get high alerts, so you’re only notified about high glucose after a period you specify.
FreeStyle Libre 3 and 3 Plus do not offer a Delay 1st High alert.
7. AID/insulin pump compatibility
For some who have diabetes, using an automated insulin delivery (AID) system or insulin pump paired with a CGM can be the best way to manage diabetes.** This can make it easier to stay in range and remove some of the guesswork from insulin dosing. But compatibility varies depending upon which CGM
you choose.
Dexcom is the leader in AID compatibility,1 compatible with the largest variety of AID systems, including iLet Bionic Pancreas, Omnipod 5, Tandem Mobi, and Tandem t:slim X2 insulin pump.
FreeStyle Libre 3 Plus is only compatible with iLet Beta Bionic Pancreas and the twiist™ Automated Insulin Delivery System.
In addition, Dexcom G7 and Dexcom G7 15 Day are also the only CGM systems with Share and Follow†† capabilities that work while using an AID system. FreeStyle Libre CGM Systems can only connect to either the AID system or Libre LinkUp, not both simultaneously.
8. Direct to Apple Watch
Dexcom G7 and Dexcom G7 15 Day connect Direct to Apple Watch. That means the sensors can send CGM data right to your watch, so you don’t need your phone nearby to see your glucose numbers.‡‡ View a list of compatible Apple Watches here.
FreeStyle Libre 3 does not offer Direct to Watch compatibility.
9. Support for more types of people
Dexcom CGM Systems are also indicated for a wide range of people living with diabetes. Dexcom G7 15 Day is for adults ages 18+ with type 1, type 2, or gestational diabetes.5 Dexcom G7 can be used for children as young as two years old.2
FreeStyle Libre 3 can be used by people ages four years and up and is approved for use during pregnancy and gestational diabetes.6 FreeStyle Libre 3 Plus can be worn by children as young as 2 years old.7
Find out if Dexcom G7 is the right CGM for you
Dexcom is the most recommended CGM brand by both doctors and patients.3,4 Dexcom G7 CGM Systems are designed to support the way you manage diabetes, making it simpler, more intuitive, and pain-free. Their flexible features make it easy to personalize your experience, so you can get the most out of CGM technology and monitor your glucose levels with greater confidence.
Get a Free Dexcom G7 Trial
Are you living with diabetes and not using CGM? Talk to your doctor about Dexcom G7 15 Day. We can also help you get started with a free benefits check. Click the button below to send us some basic information.
Dexcom G7 15 Day is for ages 18+ years *For a list of compatible devices, visit dexcom.com/compatibility. ‡Dexcom G7 can complete warm-up within 30 minutes, whereas other CGM brands require up to an hour or longer. §Individual pricing may vary depending on insurance coverage. ||A study was conducted to assess the sensor life where 73.9% of sensors lasted the full 15 days. When using the product per the package labeling, approximately 26% of sensors may not last for the full 15 days. ¶Excludes implantable CGM systems. #Audible and visual notification of predictive alert at 55mg/dl within 20 minutes. **To learn more about insulin pump integrations and compatibility with Dexcom CGM Systems, visit dexcom.com/integrate. ††Separate Follow app and internet connection required. ‡‡Compatible smartphone is required to pair a new Dexcom G7 sensor with a compatible Apple Watch. To use Share/Follow your compatible Apple Watch must be connected to the internet via Wi-fi. §§Patients reported that 94% of Dexcom G7 sensor insertion was painless (mild, no discomfort).
1 Dexcom, data on file, 2025. 2 Dexcom G7 User Guide. 3 Seagrove Patient Survey 2024. 4 Seagrove HCP Survey Q3 2024. 5 Dexcom G7 15 Day User Guide. 6 Freestyle Libre 3 User Guide. 7 Freestyle Libre 3 Plus User Guide. 8 Beck RW, et al. JAMA. 2017;317(4):371-378. 9 Beck RW, et al. Ann Intern Med. 2017;167(6):365-374. 10 Martens T, et al. JAMA. 2021;325(22):2262-2272. 11 Laffel LM, et al. JAMA. 2020;323(23):2388-2396. 12 Garg SK, et al. Diabetes Technol Ther. 2025;27(6):413-502. 13 Welsh JB, et al. J Diabetes Sci Technol. 2024;18(1):143-7. 14 Heinemann L, et al. Lancet. 2018;391(10128):1367-77.
BRIEF SAFETY STATEMENT: Failure to use the Dexcom Continuous Glucose Monitoring System and its components according to the instructions for use provided with your device and available at https://www.dexcom.com/safety-information and to properly consider all indications, contraindications, warnings, precautions, and cautions in those instructions for use may result in you missing a severe hypoglycemia (low blood glucose) or hyperglycemia (high blood glucose) occurrence and/or making a treatment decision that may result in injury. If your glucose alerts and readings from the Dexcom CGM do not match symptoms, use a blood glucose meter to make diabetes treatment decisions. Seek medical advice and attention when appropriate, including for any medical emergency.
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