Review of Dexcom G6
Pros & Cons: Dexcom G6 Continuous Glucose Monitor (CGM)
If you’re looking for a continuous glucose monitoring system to add to your diabetes toolbox, it may be daunting to figure out which system best fits your needs and priorities. We break down the Dexcom G6 CGM System for you here with details on its features and function, including key benefits and drawbacks.
The Dexcom G6 Continuous Glucose Monitoring (CGM) system was released in Canada in September of 2019. It is the most recent Dexcom version currently available in Canada.
The Dexcom G6 system is made up of three components:
- Sensor – measures glucose levels just underneath the skin
- Transmitter – fastened on top of the sensor, it sends data wirelessly to a compatible smart device or an optional receiver
- Display Device – can be any compatible smart device with the Dexcom G6 app, or an optional Dexcom receiver
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Top 6 Benefits of Dexcom G6
1. No More Fingersticks!
With G6, we don't have to do an independent BG meter check to calibrate the sensor or to make treatment decisions (should I take a low treatment? should I give insulin to correct a high? how much?). (Unless, the company reminds us, our glucose alerts and readings from the G6 do not match symptoms or expectations, in which case it’s wise to use a blood glucose meter to make treatment decisions.)
2. Sensor & Inserter
Dexcom G6 sensors last 10 days (3 days longer than Medtronic sensors, which last 7 days; but 4 days less than Libre sensors). The sensors are easy to insert, with a one-click inserter. The insertion needle is hidden within the plastic casing (see the auto-inserter with the orange button in the image near the top of this page), so you don't see the needle. Most importantly, your kids don't see the needle, making the whole insertion process less intimidating.
3. Glucose Readings at a Glance (or a Whisper)
Continuous glucose readings are sent automatically via Bluetooth to any compatible smart device, or to a Dexcom receiver, at five-minute intervals. This means your child doesn’t have to scan to check her glucose, she can just glance at the display device.
In addition to being able to view glucose values on a phone, you can also view them in real-time on a smartwatch. In this example, the 8.0 mmol/L near the top left is the current glucose level, while the diagonal-down arrow shows the glucose trend (glucose is falling slowly).
(Note that the transmitter does not communicate with the watch directly – a phone or smart device is still required.)
Want to listen instead? Just set up Siri shortcuts in your Dexcom G6 app settings, and then ask "Hey Siri, what's my glucose?" She'll speak your sensor reading - without you having to open the app.
4. Remote Monitoring in Real Time
Not only can your child see their glucose readings at a glance – so can you. Even when you’re not with them.
With the Dexcom G6 app, the CGM user can share their blood glucose levels with up to 10 Followers (Following requires the Dexcom Follow App and an Internet connection). This means that loved ones can remotely view the CGM user’s glucose data in real time. Parents can see their child’s glucose reading and trends even when their child is at school, out on the soccer field, or sleeping over at a friend’s house.
Tips from the Trenches
Remote viewing of my son's glucose data has quickly become my favourite CGM feature! I can check in while he's at school or over at his best friend's home while still giving him the independence he craves. And if things look iffy, I can text him to make sure he's treating a low or correcting a high.
You can only remotely view data if you use a smart device as the receiver (not the dedicated Dexcom receiver). We use an iPod as our son's receiver, since they are less expensive than phones (and we aren't quite ready for our 10-year-old son to have all the access that a phone allows!). Also, if we need to communicate more than a number, our son can text us (over wifi) on the same device.
How does remote monitoring improve real life with type 1?
No more “what’s your number?” ambushes. Now, when your child gets home from school, you can focus on what their day was like and what they learned instead of immediately asking them to check their blood sugars.
Parents can say “yes” to sleepovers. Since you can see what’s happening with your child’s glucose readings and trends, even from blocks (or many kilometres!) away, you can check in without having to be there next to your child; you can intervene if needed, and back off to give your child independence if all’s well.
Parents can get some sleep! You don’t need to get up to go to your child’s room to prick their finger to get a glucose number. One glance at your smartphone can tell you their glucose level and the direction it’s heading. Or, since you receive an alert on your smartphone if glucose falls below the low threshold that you set, you can choose to sleep through the night.
Tips from the Trenches
A note about sleep...
I LOVE being able to glance at our son's glucose reading in the middle of the night without getting up. But unfortunately for us, we also get low glucose “false alarms”: When our son lays on the sensor, it reads lower at the sensor site (let’s say, 3.0 mmol/L) than his glucose actually is (a fingerstick commonly returns BG results in the 5’s at these times, and sometimes in the 7’s or 8’s). So getting more sleep is still a theoretical benefit for us, not yet a reality. We are experimenting with alternate sites right now, and hope that will resolve the issue.
In the meantime, however, the Dexcom still has value for us, as it has recently woken us in the night for a legitimate low, one that we wouldn’t have known about and wouldn’t have had the opportunity to treat if the CGM system had not alerted us. ~Michelle
I would love to hear about your experiences with this, and any tips you may be able to pass along!
How does remote monitoring work?
There are 2 sides to the remote-glucose-viewing equation:
- The person with diabetes wears the sensor/transmitter; the transmitter communicates via Bluetooth with the CGM-user’s phone or smart device using the Dexcom G6 app. With the Share feature of the Dexcom app turned on, the user gives up to 10 people permission to follow the data.
- In order to follow, the parent installs the Dexcom Follow app onto their own phone / smart device. You must have an internet connection to access the data.
(The Dexcom G6 and Dexcom Follow apps are available for both iOS and Android – see www.dexcom.com/compatibility for the list of compatible devices)
Tips from the Trenches
If you’re concerned about sending an expensive smartphone to school or basketball practice with your child, consider using a less-expensive iPod Touch as the receiver. Your child will need to be able to access wifi at school (iPod Touch doesn't have data access like a smartphone does).
Tips from the Trenches
If you have problems with Signal Loss (loss of communication between the transmitter and receiver) when you use your smartphone as the receiver , it may be because there are too many apps competing for the Bluetooth signal. To resolve this issue, it helps to power your phone completely off at least once a day; I’ve made it a habit to do this every night before bed, and it almost completely resolved my problems with signal loss. You can change your settings so that Dexcom takes priority in terms of signal assignment (call Dexcom tech support for help with this if you’re unsure how to do it).
- Person with Diabetes / Dexcom User
5. Glucose Alerts
CGM measures your glucose levels continuously, even when you’re not attending to it – so it can notify you of highs and lows (even those that you may have missed) based on alerts that you set.
The Dexcom G6 alerts include:
- Low Glucose Alert - lets you know when your glucose crosses a lower threshold that you set
- High Glucose Alert – notifies you when your glucose crosses an upper threshold that you set
- Rate of Change Alerts – tell you when your glucose is rising or falling rapidly
- Urgent Low Soon alert – warns users up to 20 minutes in advance of an urgent hypo (glucose lower than 3.1 mmol/L), so you can take steps to prevent it
Tips from the Trenches
If you set the Low Alert slightly higher than when you would typically feel low, this will allow you to “catch” the low and act to avoid it before it happens.
For extra safety, the Dexcom CGM System includes a fixed hypo alarm which cannot be adjusted or turned off:
- Urgent Low Glucose Alarm is fixed at 3.1 mmol/L. If your glucose falls below this level, the alarm will go off every 30 mins until glucose has risen above 3.1 mmol/L.
You can choose which alerts you want turned on or off, and can change & customize them at any time. There's also more flexibility with G6 alerts: you can set different alert levels for the night-time vs. the day.
How can alerts improve real life with type 1?
Alerts can help catch lows before they happen. This is particularly important for anyone who doesn’t feel their lows (hypo unaware), and especially for parents of young children who may not reliably detect their lows or be able to communicate lows to parents.
The Rate of Change Alerts give you a heads-up when blood sugars are changing quickly, which is particularly important if blood sugars are crashing. The same is true of highs: there is also a Rate of Change Alert for rapidly increasing glucose levels, which gives you the opportunity to get a dose of correction insulin in earlier, if you choose.
Parents can receive high and low glucose alerts on their mobile device, and can program the alert levels and tones as appropriate; each person can choose how and when they would like to receive alerts. For example, the child’s smart device/receiver may have the low alert set to 4.0 mmol/L, while the parent’s low alert could be set to 5.0 mmol/L, to give more advance warning of a low.
6. You don't have to Pump to use CGM
Dexcom G6 is a stand-alone system, you don’t need to be on an insulin pump to use it. So individuals on injections can also use this CGM system to reduce fingerpokes, to catch undetected glucose extremes, and to gather information about patterns and trends.
A study (4) in the early days of CGM use showed that CGM provides similar benefits in glucose control for both patients on MDI and those on insulin pump therapy: less time was spent in both hypoglycemic and hyperglycemic ranges. In addition, a 2018 randomised controlled trial (5) demonstrated that using real-time continuous glucose monitoring reduced the number of hypoglycemic events (lows) in individuals with type 1 diabetes treated by MDI and with impaired hypoglycemia awareness or severe hypoglycemia: the average number of hypoglycemic events (per 28 days) among participants in the real-time continuous glucose monitoring group was reduced from 10.8 to 3.5, while reductions among control participants (without CGM) were negligible. (Both studies received funding from Dexcom, Inc.)
The Dexcom G6 System has been shown in independent research studies to provide accurate glucose readings in adults and children throughout its 10-day sensor life.
But just how accurate is it? One study (Shah et al) showed that overall average Sensor Glucose values (MARD), when compared to lab analyzer blood glucose values (using a blood sample taken from a vein) were within 7.7% for children¹ and 9.8% for adults¹. That accuracy is maintained even when glucose is rising or falling (typically a weak spot for previous CGM systems). Another study (Wadwa et al) showed that when glucose was falling or rising, 9 out of 10 Dexcom G6 readings were within ±20% of the lab analyzed value (for readings over 5.5mmol/L, and within ±1.1 mmol/L for readings 5.5 or lower).²
Because of this accuracy, Dexcom is approved to replace fingerstick testing for treatment decisions – in any blood glucose range. That means that when the G6 reads your glucose as low, you don’t need to confirm that reading with a fingerstick check before treating the low with fast-acting glucose. It also means that when the G6 reads your glucose as being above your target range (high glucose), you don’t need to confirm that with a fingerstick check before dosing insulin to correct the high. After all, the standard for accuracy for fingerstick glucose meters is 10%, which Dexcom matches or exceeds for both kids and adults.
Finally, the G6 sensor accuracy is not affected by acetaminophen use. So if you give your child up to 1,000mg (every six hours) of Tylenol® for aches, pains or a fever, you don't have to go back to fingersticks. (Any more than that dose, however, may affect Sensor Glucose readings.)
MARD = mean absolute relative difference = the average of the relative difference between paired CGM and gold-standard lab analyzed values of venous blood samples
How does accuracy impact life with Type 1?
Accuracy is critical when it comes to trusting any continuous glucose monitoring system and its utility in real life. An accurate system is one you can trust. Only if you trust the displayed glucose value can you skip the fingerstick check, saving you time and hassle.
Tips from the Trenches
Our family has lived with many different CGM systems over the past 10 years, from the Dexcom 7+, through all the G's, and also Medtronic CGM., and I can tell you that when the accuracy is off for any reason, wearing CGM is useless. If we have to keep doing a fingerpoke for multiple alarms in a day, or to calibrate, and then to calibrate again 20 minutes later because the number we entered was too far away from what the sensor believed it should be... well, all of that makes wearing a CGM more trouble than it's worth. And there have been many times that we've taken a CGM break for exactly that reason. But wearing the G6 was a turning point for our family. No, the technology isn't perfect, but now we feel that it helps much more than it hinders, and we trust the system enough to bolus insulin when it says SG is high, and take a low treatment when it says SG is low or about to be low. That's a win! ~Michelle
Our son loves that he can skip most fingerstick checks while he’s at school. He just glances at the display, and uses that glucose reading to either treats a low or to give a correction dose of insulin. This means he’s going with the other kids to gym, to snack, to lunch, without having to stop for a fingertsick check. ~Michelle
Other Things to Know About Dexcom including the Drawbacks
In addition to the sensor glucose number, the Dexcom G6 also displays trend arrows that indicate the direction blood glucose is headed, and how quickly it’s moving:
The auto-applicator is designed to make sensor insertion simple with the touch of a button. But it's big, and you throw it away after you use it, which always makes me cringe on behalf of the environment. (Clearly not enough for us to stop using Dexcom, though...)
Sensors are good for up to 10 days. Dexcom will replace the sensor free of charge if it doesn’t last 10 days.
You may need to reinforce the adhesive patch with various tapes and skin prep products to keep the sensor on for 7 full days.
You may need to use skin prep products and protective tapes under the adhesive patch to manage a possible skin reaction.
The only sensor sites approved by Health Canada for kids are the abdomen and upper buttocks. But you may find success experimenting with other sites; I've heard of adults and kids having success with the side of the waist, the back of the upper arm, and the inner upper thigh.
The (optional) G6 receiver has a touchscreen display. Though our family prefers to use a smartphone or iPod, the big advantage of the dedicated receiver is that you don't have the hassle of random signal loss, as there's no other functionality to interfere with receiving glucose readings.
The G6 transmitter is slim and has a low profile. It's not as flat as the Libre or Libre 2, but does have a smaller footprint.
The G6 transmitter batteries are non-rechargeable and will work for just over 3 months (112 days); at that point, the transmitter will automatically shut off. An alert will notify you if it’s expiring soon; the system won’t let you start a new sensor if the transmitter will expire during that sensor session.
I find this hard stop frustrating, as it means that you need to pay for a new transmitter (almost $300!) every 3 months. If you don't use CGM full-time, you can't pause the transmitter or save the time for when you do use it - the clock starts ticking as soon as you take it out of the box, whether you use CGM for all 3 months or for only a few weeks. As a family that has historically used CGM intermittently because of our son's sensitive skin, this makes the "per use" cost very high! ~Michelle
Tips from the Trenches
Plan to replace the transmitter every 3 months, even though the battery lasts a few weeks longer than that. Then you will have a “buffer” until the transmitter actually stops, giving you time to order one if needed.
Shah VN, Laffel LM, Wadwa RP, Garg SK. Performance of a Factory-Calibrated Real-Time Continuous Glucose Monitoring System Utilizing an Automated Sensor
Applicator. Diabetes Technol Ther. 2018.
Wadwa RP, Laffel LM, Shah VN, Garg SK. Accuracy of a Factory-Calibrated, Real-Time Continuous Glucose Monitoring System During 10 Days of Use in Youth and
Adults with Diabetes. Diabetes Technol Ther. 2018.
Laffel. Improved Accuracy of Continuous Glucose Monitoring Systems in Pediatric Patients with Diabetes Mellitus - Results from Two Studies. Diabetes Technol Ther 2016; 18 (Supp 2).
Garg SK, Voelmle MK, Beatson CR, et al. Use of Continuous Glucose Monitoring in Subjects With Type 1 Diabetes on Multiple Daily Injections Versus Continuous Subcutaneous Insulin Infusion Therapy: A prospective 6-month study. Diabetes Care. 2011; 34(3):574-579. doi:10.2337/dc10-1852.
Heinemann, Lutz et al. Real-time continuous glucose monitoring in adults with type 1 diabetes and impaired hypoglycaemia awareness or severe hypoglycaemia treated with multiple daily insulin injections (HypoDE): a multicentre, randomised controlled trial. The Lancet, 2018; 391(10128): 1367 – 1377.
The above information was reviewed for content accuracy by a representative of Dexcom Canada.
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