It’s time to compare the new continuous glucose monitoring devices from Dexcom and Freestyle Libre – the G7 and Libre 3.
Dexcom and Abbott have been at the forefront of continuous glucose monitoring since the late 1990s. Their latest CGM devices have been on the market for some time, with lots of Freestyle Libre 3 and Dexcom G7 reviews out there. But reviews and data sheets don’t always make choosing the best CGM any easier.
Continuous glucose monitoring makes diabetes management so much easier, especially for children with type 1 diabetes. Gone are (most of) those messy and uncomfortable finger pricks. Gone are the bloodstained, handwritten diabetes diaries!
Today’s CGMs bring diabetes care into the digital age with a bang. Through Bluetooth connections with smartphones, you can monitor every peak and dip in your child’s glucose measurements throughout the day and night, even when you are separated.
Of course, this new technology isn’t failproof. False readings, bad connections, faulty sensors, and knocks and bumps all affect CGM reliability. So exactly how reliable is the Dexcom G7? And is the Freestyle Libre 3 safe to use? Let’s find out.
Who Are CGMs for?
Scroll through TikTok and YouTube, and you’ll find plenty of CGM how-to videos from people who aren’t diabetic. That’s because we now know that even non-diabetics suffer from glucose highs.
But for adults and children with T1D, continuous glucose monitoring is essential. Keeping highs and lows at bay isn’t easy, and even hourly finger sticks don’t measure up to the detailed curves of an interstitial tissue glucose monitoring system.
Dexcom G7 vs Freestyle Libre 3
Developed by Dexcom and Abbott respectively, G7 and Libre 3 sensors do the same thing. They continuously measure glucose in interstitial fluid and store the data for a specific period. When connected to a compatible reader or smartphone via Bluetooth, this data is transmitted – there’s no need for an Internet connection.
The accompanying CGM app is where data is turned into easy-to-read daily curves, estimated HbA1c levels, times in range, high and low percentages, and other helpful information.
They can also both pair easily with Gluroo, our free diabetes management app that works like a chat app. Connecting your Libre 3 or G7 to Gluroo lets you easily share your BGL data with other people in your GluCrew, along with things like insulin on board, carbohydrate announcements, and more.
Both devices are available on or off prescription, but at the time of writing only the Dexcom G7 is covered by Medicare. Abbott Diabetes Care has applied for Medicare approval for the Libre 3 sensor. If you have private or employer medical insurance, it might be worth asking if both devices are covered.
Let’s jump into the comparison, where we’ll be looking at each device’s features, performance, pricing, user experience, and usability.
The G7 overview page on the Dexcom website says in big green letters that no finger sticks are necessary. However, as users regularly complain about inaccurate results, matching interstitial results with an occasional finger stick test is a good idea. Just don’t forget that interstitial readings are not the same as blood readings.
Glucose in the watery fluid in our tissues is brought there via the bloodstream. This means interstitial glucose values can be up to 30 minutes behind blood glucose measurements. Exercise can make these two readings very different.
Interstitial glucose values give more useful information than glucose levels in the blood. After all, it’s in tissue cells that glucose is absorbed and used. Researchers tell us interstitial glucose data gives a better picture of how the body uses and reacts to this source of immediate energy.
Let’s look at some more Dexcom G7 features.
The G7 sensor is smaller than the Dexcom G6 and almost round. It measures 0.94 x 1.08 x 0.18 inches and should be placed on the back of the arm or abdomen. Young children may wear it on the upper buttocks. According to Dexcom, if you place the sensor on any other site and it becomes faulty or damaged, it won’t be replaced via Dexcom Tech Support.
The G7 sensor lasts for 10 days. A top G7 feature is the Grace Period, where a new sensor can be applied just before the old one runs out. This means you can avoid the short 30-minute warm-up period without wasting any of that precious (and expensive) 10-day lifespan.
If your child with diabetes is a water rat, the Dexcom G7 might be the best CGM choice. Unlike the Libre 3, this sensor can be submerged for up to 24 hours at a depth of 8 feet. Children as young as 2 years old can use this sensor.
While the earlier G6 CGM had a separate transmitter, the G7 is an all-in-one solution. Developers still have work to do as the transmission range is low. If your smart device or reader aren’t within 20 feet, data won’t be transmitted. Some users say transmission only occurs within 6 feet, although this might be caused by the quality of a smart device’s Bluetooth capabilities.
The Dexcom G7 app sends your choice of loud or quiet alerts up to 20 minutes before an estimated hypo, although it’s possible to make all alerts silent.
Tha main screen of the app gives you the option to select measurements over 3, 6, 12, or 24 hours. It’s easy to read and navigate, supplying helpful information for users and others the user permits access to.
The Abbott Diabetes Care Libre 3 is the smaller of the two CGM sensors at just 0.83 x 0.83 x 0.11 in. Like the recent Dexcom G7, there’s no need to scan as data is sent between sensor and smart device via Bluetooth. The transmission range of the Libre 3 is significantly higher at 33 feet. However, for swimmers there’s a downside – the Libre 3 has a limit of 3 feet water depth for up to 30 minutes.
Warm-up time is 60 minutes as there’s no Grace Period option. There’s also no way to turn off the loud low glucose alarm. Which, for many parents of children with diabetes is a good thing, and for many adults with diabetes is a very annoying thing. You can turn off other alarms, just not the low glucose one (unless you disable Bluetooth).
The sensor sends data to the paired smart device every minute, so you get a slightly more detailed curve than with the G7 which only sends data every 5 minutes. This is useful for recently diagnosed diabetics, or diabetics who experience lots of peaks and dips during the day and/or night.
Each sensor lasts 14 days, 4 days more than the Dexcom G7. However, as sensor placement is painless with both models, sensor lifespan shouldn’t be a deal breaker.
The youngest approved age for Freestyle Libre 3 sensor use is 4. For young children, placement is on the upper buttock. For older children and adults, the only approved placement is the back of the upper arm. Faulty sensors won’t be replaced by Abbott Diabetes Care if they have been placed on other parts of the body.
The accompanying Libre 3 app is simple to use and easy to navigate. The home screen features the latest glucose reading with trend arrows, and a 12-hour graph. You can use the LibreLinkUp app to remotely connect to 20 people and you can share data with health professionals via LibreView. The app is also voice accessible.
The most important metric of CGM performance is accuracy. CGM accuracy is measured as MARD% – in this case the average difference between reported and true interstitial glucose values. A good MARD value is under 10%. The Dexcom G7 makes the grade with 8.1% for adults and 8.2% for children (on the back of the arm or upper buttocks respectively).
Other G7 performance metrics worth mentioning are its good water resistance and easy and attractive app. As with the Libre 3, integration scores are very low with plans for pump integration still on the drawing board. If your child uses a hybrid insulin pump, stick with the G6 until the G7 is integration ready. Dexcom’s claim, “The most connected CGM brand in the world” doesn’t (yet) include the G7. It should also be mentioned that Dexcom G7 data storage capacity is low – just 24 hours of data can be stored at any one time.
In terms of performance, the Libre 3 wins. In fact, the Dexcom G7 is more comparable to the older Libre 2 than the latest Abbott CGM sensor. Details like insurance coverage, water resistance, warm-up time, and Grace Period might be enough to sway a decision in the opposite direction.
The sensor memory of the Libre 3 can store 14 days of data – if you lose your phone and have to wait for a replacement, you won’t lose precious blood glucose results. Interstitial glucose is measured every minute. The (unobstructed) transmission range is a generous 33 feet.
The Libre 3 sensor is insulin-pump ready in Europe.
This sensor also gets a higher accuracy score – 9.2% for adults and 9.4% for children. However, the 1% difference in accuracy between these devices isn’t so huge.
Price & Monthly Cost
If you have a government health care plan, the Dexcom G7 is the only covered option in this CGM comparison. Private and employer health insurance companies may provide Libre 3 cover, so check first.
A CGM prescription or CGM reader is not required.
Dexcom G7 sensor price is $340 for a pack of 3 ($120 for a single sensor). The G7 lasts 10 days, meaning 12 packs a year.
This means a total annual Dexcom G7 cost of approximately $4,080 ($340 a month).
The Libre 3 price is $75 per sensor. Each sensor lasts 14 days, meaning 26 sensors per year.
This means a total annual Libre 3 cost of approximately $1,950 ($165 a month).
Usability, Comfort, Popularity, and User Experience
Dexcom G7 reviews are quite critical, mentioning:
- Compression lows (low glucose readings caused by pressure to the sensor while sleeping) that set off the hypo alarm in the middle of the night.
- Sensors don’t last for the full 10 days (calling the free 24/7 Tech Support line and reporting all necessary information after a Failed Sensor alert means a free replacement).
- Accuracy glitches, especially when glucose levels are particularly low or high.
- Loss of signal alerts that most users turn off because they are so annoying.
However, as the most popular CGM developer in the US, Dexcom must be getting it right.
Most users are happy with:
- The quality of the Android app (there’s a problem yet to be solved with the iPhone lock screen widget).
- Tech Support response (although you might have to wait a while to get through).
- The very simple set up.
- The thinner sensor that doesn’t catch on door frames as easily, and ease of sensor application.
Abbott Diabetes Care’s Libre 3 is more popular in Europe than the US. However, the technology inside this smallest ever CGM sensor doesn’t seem to compromise signal transmission as it seems to with the Dexcom G7.
Upgrades from the Libre 2 include a simpler application method which users find important, but it’s the no need to scan part that makes the biggest difference. There are also some reports of compression lows and inaccurate results when compared to finger stick results.
European Libre 3 users wait less than 10 minutes to speak to human tech support when a sensor stops working before its 14-day lifespan. The same isn’t as true for US customers who often need to wait much longer.
A word of warning – one non-insured US user who bought a two-pack from a pharmacy couldn’t get a replacement from Abbott customer support or return a single faulty sensor to the pharmacy. But this type of complaint isn’t common.
By far the biggest complaint with the Libre 3 is the mandatory low glucose alarm and the inability to set any alarm to vibrate. One user even says the app has less features than would be expected in a free alarm clock app.
But as far as accuracy is concerned, the Libre 3 is the top CGM on the list with a MARD% of 9.4 for children and 9.2 for adults. With results transmitted (or stored) every minute, you won’t get a more detailed or accurate interstitial glucose curve on any other device.
|Dexcom G7||Freestyle Libre 3|
|Sensor dimensions (inches)||0.94 x 1.08 x 0.18 in (24 × 27.3 × 4.6 mm)||0.83 x 0.83 x 0.11 in (21 x 21 x 2.9 mm)|
|Waterproof||Shower and bath safe|
24 hours at 8 feet
|Shower and bath safe|
30 minutes at 3 feet
|Minimum age (years)||2||4|
|Accuracy (MARD%) adult||8.2||9.2|
|Accuracy (MARD%) child||8.1||9.4|
|Warm up time||30 min||60 min|
|Wear time||10 days||14 days|
|Number of transmissions/minute||12||60|
|Transmission range (feet)||20||33|
|Grace Period after new sensor insertion (hours)||12||0|
|Current sensor integrations||None|
(Future plans for Tandem ControlIQ, InPen and Omnipod 5 integration)
|mylife™ Loop automated insulin delivery system (Europe)|
(Future plans for Tandem and Insulet integration)
|Sensor memory when out of range (days)||1||14|
|Compatibility||Dexcom G7 app||LibreLink app|
|Pairs with:||Specified Android and iOS devices||Specified Android and iOS devices|
|Data sharing?||Up to 10 people||Up to 20 people|
|Warranty||Sensor: not covered, but replaced when faulty||Sensor: not covered, but replaced when faulty|
|Average monthly cost (sensors only) without CGM insurance cover||$340 (30 days)||$150 (28 days)|
Unfortunately, most healthcare decisions are dictated by the health care insurer. Medical supply costs are notoriously high, and the right to choose is not always financially viable.
So, while the Libre 3 seems to be the better device (unless you’re a pool-loving 3-year-old), its lack of government health insurance coverage puts it out of reach for many people with diabetes. Once Medicare approves the Libre 3, its lower price and better transmission might make it the best CGM choice within the US.
But CGM technology is still in its early days, and the three CGM giants – Dexcom, Medtronic, and Abbott – are all working on development of a low cost, error-free, accurate, high integration interstitial glucose sensor for diabetics.
The G7 and Libre 3 might offer the best CGM technology of 2023, but their reigns won’t last. The future of interstitial glucose monitoring is exciting and bright.