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Continuous Glucose Monitoring (CGM) System

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 it down for you here, with an overview of the Dexcom G5 Mobile CGM System, and its key benefits.

The Dexcom G5 Mobile CGM System is made up of three components:

  1. Sensor – measures glucose levels just underneath the skin
  2. Transmitter – fastened on top of the sensor, it sends data wirelessly to a compatible smart device or an optional receiver
  3. Display Device – can be a Dexcom G5 Mobile Receiver or any compatible smart device with the Dexcom G5 Mobile app
More on CGM system components:
What is a Continuous Glucose Monitor?

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The Dexcom G5 Mobile CGM system was released in Canada in January of 2017. It is the most recent Dexcom version currently available in Canada.

Top 5 Benefits of Dexcom G5

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1. Glucose Levels at a Glance

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.)

2. CGM is not just for pumpers anymore

Since the Dexcom G5 Mobile is a stand-alone system, you don’t need to be on an insulin pump to use it; 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 (6) 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 (7) 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.)

3. 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.

Dexcom G5 can alert you when:

  • your glucose crosses a lower threshold that you set (Low Glucose Alert)
  • your glucose crosses an upper threshold that you set (High Glucose Alert)
  • your glucose is rising or falling rapidly (Rate of Change Alerts)


You can choose which alerts you want turned on or off, and can change & customize them at any time.

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 before it happens, and intervene if necessary.

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.
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.

4. Remote Monitoring in Real Time

With the Dexcom G5 Mobile app, the CGM user can share their blood glucose levels with up to 5 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). And this isn’t the only reason that we prefer the iPod-as-receiver approach: the dedicated receiver doesn’t back-fill data like the app does, and (as mentioned above) with his iPod he can text us about diabetes 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

Please let me know 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:

  1. 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 G5 Mobile CGM app. With the Share feature of the Dexcom G5 Mobile app, the user gives up to 5 people permission to follow the data;
  2. In order to follow, the parent installs the Dexcom Follow app onto their own phone / smart device, and must have an Internet connection to access the data.

(The Dexcom G5 Mobile and Dexcom Follow apps are available for both iOS and Android – see 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).
– PWD and Dexcom G5 User

5. Accuracy

The Dexcom G4 Platinum System (previous generation Dexcom) was shown in independent research studies to have the best-in-class sensor accuracy (1,2,3) of any CGM system available in Canada. But just how accurate is it? To illustrate, two research studies on the clinical accuracy of earlier generation Dexcom systems showed that overall average glucose sensor values (measured as mean absolute relative difference, or MARD), when compared to lab analyzer blood glucose values (using a blood sample taken from a vein) were within 10% for children (4), and 9% for adults (5). It follows logically that tech advancements have made the Dexcom G5 Mobile CGM System at least as, or more, accurate. 

Further, the Dexcom G5 Mobile is the only CGM system approved to replace fingerstick testing for treatment decisions – in any blood glucose range. That means that when the G5 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 G5 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. You only need to calibrate the sensor twice per day with a fingerstick measure.

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 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

What else should I know about Dexcom?

  • In addition to the blood glucose number, the Dexcom G5 Mobile also displays trend arrows that indicate the direction blood glucose is headed, and how quickly it’s moving.
  • Sensors are good for 7 days. Dexcom will replace the sensor free of charge if it doesn’t last 7 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 G5 transmitters have the same footprint as the previous G4 transmitters, making the transition from G4 to G5 simpler, even in the middle of a box of sensors, as the same sensors are compatible with both systems. The G5 transmitter is slightly thicker than the G4, to meet the processing needs of Bluetooth.
  • The G5 transmitter batteries are non-rechargeable and will work for 112 days (less time than the previous G4 transmitters because Bluetooth takes lots of energy to run); 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.

Tips from the Trenches

If you plan on replacing the transmitter every 3 months, even though the battery lasts a few weeks longer than that, you will have a “buffer” until the transmitter actually stops, giving you time to order one if needed.


1. Damiano E, et al. A Comparative effectiveness analysis of three continuous glucose monitors: the Navigator, G4 Platinum, and Enlite. J Diabetes Sci Technol 2014; 8(4):699-708.

2. Matuleviciene V, et al. A clinical trial of the accuracy and treatment experience of the Dexcom G4 sensor (Dexcom G4 System) and Enlite sensor (Guardian REAL-Time System) tested simultaneously in ambulatory patients with type 1 diabetes. Diabetes Technol Ther 2014; 16(11):1-9.

3. Kropff J, et al. Accuracy of two continuous glucose monitoring systems: a head-to-head comparison under clinical research center and daily life conditions. Diabet Obes Metab 2014. Doi: 10.1111dom.12378, Epub 10 Sept 14.

4. 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).

5. Bailey, Chang, Christiansen. Clinical Accuracy of a Continuous Glucose Monitoring System with an Advanced Algorithm. J Diabetes Sc Tech 2015; 9(2): 209-214.

6. 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.

7. 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.

This material has been developed from sources that we believe are accurate, however, as the field of medicine (in particular as it applies to diabetes) is rapidly evolving, the information should not be relied upon, as it is designed for informational purposes only. It should not be used in place of medical advice, instruction and/or treatment. If you have specific questions, please consult your doctor or appropriate health care professional.

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