Avoid These Freestyle Libre Mistakes for Accurate Glucose Readings
If you’re deciding between Freestyle Libre 3 and Dexcom G7.
This article will outline what they have in common, where they differ, allowing you to make an informed decision based on your preferences.
First, we need to talk about what these devices do and what they have in common.
These systems are great tools to continuously monitor your glucose level without pricking your fingers. You place a patch with a tiny sensor on your skin, and both sensors automatically feed all your glucose data to your receiving device via Bluetooth. You don’t need to do anything. Your numbers and glucose graphs are automatically saved on your device.
One thing you need to know when you are starting on one of these devices is that these devices do not measure your blood glucose levels. CGM sensors read your glucose levels from interstitial fluid, the body fluid between blood vessels and cells.
They don’t measure your actual blood sugar, but they give you an excellent indication of your blood sugar.
Actual blood glucose is always a few minutes ahead of the sensor blood glucose reading. Sensor readings lag slightly behind blood readings as glucose moves from the blood to interstitial fluid.
The good news is that with both G7 and Libre 3, the lag between blood and sensor readings got shorter than their predecessor.
Libre 3 and Dexcom G7 provide more real-life glucose information.
Let’s discuss the differences between the Freestyle Libre 3 and Dexcom G7.
Differences between the Freestyle Libre 3 and Dexcom G7
Made by different companies, these devices have different designs that focus on making them easy to use. The current trend in diabetes care is to connect these models to online platforms for virtual monitoring. Both the Libre 3 and Dexcom G7 are good at this, using different methods to send information remotely. This review outlines the significant distinctions between the two devices. Let’s discuss the differences between the two devices below:
1. Sensor Design
Both of these sensors come in tiny compact packages. Libre 3 has a slightly smaller box and applicator, but the packaging is fairly comparable overall.
The Dexcom G7 has a free overlay patch that you can place over the sensor to help keep it secure. Freestyle Libre 3 doesn't come with an overlay.
With Libre 3, you unscrew the lid, unscrew the applicator over the side, push the top of the applicator down to apply the sensor, and then gently pull the applicator away.
The G7 applicator with its grey rubber component also looks a bit more premium than the plastic-looking Libre 3 applicator.
Excellent work at Dexcom. But who cares about how the applicator looks?
Most people care about the sensor's appearance because they wear it 24/7.
Both of these sensors are really tiny and super light. You immediately forget they were there when you put them on your arm.
The Freestyle Libre 3 is smaller and sleeker when sitting on the arm than the G7. Although the difference in size is not huge.
The sensors have slight colour differences. Libre 3 is matte white, and Dexcom G7 is slightly greyish.
Both sensors have a little hole in them, which helps with insertion of the filament under the skin, and also to regulate temperature and humidity around the sensor.
They are water resistant, so it's perfectly fine to shower or swim with them. Freestyle Libre 3 claims to be water resistant for 30 minutes, and Dexcom G7 claims to be water resistant for 24 hours when submerged under 8 feet of water.
Although we like the look of both of these sensors a lot given their smaller, sleeker design and enhanced wearability, the decision between the two ultimately rests on your personal preference.
2. Sensor Sites and Site Change Process
Libre 3 is only approved for use on the back of your upper arm. With Dexcom G7, you can also use it on your abdomen. And if you are below 18, you can use the upper buttocks. The G7 gives you more flexibility to decide where you want to place the sensor.
Many people use different sites, not just those officially approved. But that’s a topic for another day. To show you which sensor is better when it comes to the site change process. You need to understand a few basic terms.
Sensor Life
First is sensor wear time. Sensor wear time tells you how many days you can use your sensor before it stops working and before replacing it with a new one.
The wear-time of the Dexcom G7 is 10 days, and the wear-time of Freestyle Libre 3 is 14 days. Dexcom is trying to prolong the wear time of the G7, but it’s unclear if and when it will happen. Right now, the Libre lasts 4 days longer.
Dexcom G7 gives you a special bonus. Something that’s called a grace period. It means that after you’ve used your G7 for 10 days, you can keep using it for another 12 hours before it stops providing you readings.
That’s useful because if your G7 expires in the middle of the night or the middle of an exciting activity, you don’t need to change right away. You still have 12 hours to do the site change.
Warm Up Period
The next term we need to understand is the sensor warm-up time. Sensor warm-up time tells you how many minutes it takes for the sensor to warm up after you apply it to your skin.
In other words, how many minutes do you need to wait before the sensor starts giving you your glucose number?
The warm-up time of Dexcom G7 is 30 minutes, and the warm-up time of Libre 3 is 60 mins. Dexcom G7 takes half an hour less to warm up than Freestyle Libre 3.
Dexcom didn’t stop here. Another feature of the G7 is that the warm-up time starts automatically as soon as you use the sensor. The clock starts ticking as soon as you press the sensor applicator button. So it never lasts more than 30 minutes.
With Freestyle Libre 3, you need to not only apply the sensor. You must also scan the sensor with your phone to activate the sensor. And only when you scan the 60-minute timer does it start ticking.
If you forget to scan your Freestyle Libre 3, the warm-up period won’t start, and you will have to wait even longer.
If you apply a new G7 sensor while your current G7 is running, the time on the new sensor will start automatically even though you are still receiving data from the old sensor.
You wait 30 minutes and then switch from the old sensor to the new one in the Dexcom G7 app by entering the four-digit code printed on the applicator of the new sensor or scanning the QR code.
If you follow these steps, you won’t miss any readings and won’t have a gap in your glucose graph.
With Freestyle Libre 3, the gap can’t be avoided even if you were to apply a new sensor while the old sensor is still running. You’re not able to activate the new sensor and still receive the old data from the old sensor while the new sensor is warming up.
3. Sensor Adhesive
Adherence is super important because it doesn't matter how long your sensor's lifetime is if it peels off during your first shower.
When comparing the adhesives, it's worth noting that users may observe variations in performance. For instance, some individuals find the Freestyle Libre adhesive to be effective, while others note that the Dexcom adhesive may not be as robust, potentially showing signs of peeling after a few days of wear, and vice versa. This observation is subjective and varies among users. With proper application, you can maximise adherence of either CGM.
Both of these sensor adhesives are super small. So if you're not careful, you can knock it off when walking through a doorway or taking your shirt off.
You can cover both of these sensors with an adhesive patch, especially on days when you are active.
Type Strong offers a medical-grade hypoallergenic adhesive patch for FreeStyle Libre sensor & Dexcom, offering a reliable solution to secure your continuous glucose monitoring (CGM) device.
4. Receiving Device and Integration
This is an important and often overlooked topic because users like viewing their data on different devices.
The Dexcom G7 can be paired with up to 3 devices. You can view your glucose information and graph on the G7 phone app, an apple watch, and it can now be integrated with the new t:slim 2x insulin pump.
For Freestyle Libre 3, there is no receiver. It can be paired only with your Libre 3 phone app. Unlike Dexcom, Freestyle Libre 3 doesn’t let you view your data on your watch. There is no watch app available. Libre 3 should also be able to integrate with insulin pumps in the future because it has the iCGM status. But the timeline is not clear.
5. Accuracy
Which of these two is more accurate?
Always remember, the lower the MARD, the more accurate the CGM is.
Freestyle Libre 3 has a MARD of 7.9%, and Dexcom G7 has a MARD of 8.2%. So, Libre 3 is statistically more accurate.
Both Freestyle Libre 3 and Dexcom G7 have excellent accuracy. You have no complaints, and you can’t say that one is more accurate. You might see completely different results because everyone is different.
One thing to note here is that the glucose level on Libre 3 updates every minute. With Dexcom G7, it only updates every 5 minutes. So you could say that Freestyle Libre 3 is a little more real-time. But you don’t see that big of a difference.
Another thing to consider when it comes to accuracy is the ability of the user to calibrate the sensor readings in the app. This can only be done with Dexcom G7. Freestyle Libre 3 doesn’t have a calibration feature.
6. Mobile Apps
Both Freestyle Libre 3 and Dexcom G7 apps show you the glucose graph, glucose number, and glucose trend. They have customisable alarms and offer overviews of your historical glucose data. This is a standard, but you can get a lot more from the G7 app.
With Dexcom G7, you can create 2 different alert profiles. You can sleep on your alarms for 15 minutes to 6 hours. You can delay your first high alert by 15 minutes up to an hour. You can calibrate your sensor readings to your blood readings and zoom in and out on a specific time frame. You can do so much more with the G7 app. It’s more modern and customisable than the old-fashioned, medical-looking Freestyle Libre 3 app.
We will talk more about the Dexcom G7 in a full Dexcom G7 review.
The only benefit that the Freestyle Libre 3 app has over the Dexcom G7 app is the Dark Mode. Dexcom G7 does not have that. But it doesn’t stop us from thinking that the Dexcom G7 app is better.
These apps didn’t change from the previous sensor generations. It’s the LibreLink for Freestyle Libre 3 and the Follow app for Dexcom G7.
Also, a bonus feature is that both systems have the ability to share your data with your loved ones.
7. Price
The price of Freestyle Libre 3 is around 100 AUD, and the price of Dexcom G7 is around 130 AUD.
Dexcom G7 is quite expensive, so that’s a point for Freestyle Libre. Many people have to pay out of pocket. If your insurance doesn’t cover it, this is a big deal.
The prices might be slightly different depending on your insurance coverage and the country where you live. So, always do your own research when it comes to pricing.
Summary of Differences:
Transmission frequency:
- Dexcom G7: Sends data every 5 minutes.
- Libre 3: Transmits data every 10 minutes.
Sensor Life:
- Dexcom G7: Sensor lasts for 10 days, with an additional grace period of 12 hours.
- Libre 3: Sensor lasts for 14 days.
Sensor’s Accuracy:
- Libre 3: Highly accurate with a MARD score of 7.9%.
- Dexcom G7: Slightly less accurate with a MARD score of 8.2%.
Receiving Device and Integration:
- Libre 3: only with Libre 3 phone application.
- Dexcom G7: Integrated with Tandem t:slim, SmartPens and Omnipod 5
Conclusion
Choosing between the Freestyle Libre 3 and Dexcom G7 depends on your personal preferences and priorities.
Both devices offer the convenience of continuous glucose monitoring without finger pricking. They use sensors that read glucose levels from interstitial fluid, providing a good indication of blood sugar levels. The Libre 3 and G7 have improved sensor responsiveness, providing more real-time glucose information than their predecessors.
If sleek design, longer wear time, and strong adhesive are your priorities, the Freestyle Libre 3 might be the better choice. On the other hand, if you value more advanced mobile app features and multiple device pairing and are willing to pay a bit more for these benefits, the Dexcom G7 could be the preferred option.
Consider your lifestyle, preferences, and budget when deciding, and always consult your healthcare provider for personalised advice.
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