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In the last several years, continuous glucose monitoring (CGM) strategies have become mainstream in the diabetes world. Rather than having just a few data points each day from finger pokes, rather like having a few still photos, CGM is like a movie, giving a continuous picture of blood sugars through the entire 24 hour period.
The three continuous glucose monitors available in Canada are listed below, along with some exciting new features.
The Freestyle Libre is currently in its second generation (Libre 2). Historically, the Libre has been an intermittently scanned CGM, meaning that a person has to pass their phone or reader close to the sensor (placed on the arm) to get a blood sugar reading. With the Libre 2, if blood sugar is low, the sensor would push the data to the phone or reader and an alarm would sound. As of September 2023, a new software update is available that allows the Libre 2 to continuously push blood sugars to your phone, so that scanning is not required (making it a real time continuous CGM). Once you have updated your app, the update takes effect when you start your next sensor. With this software update, caregivers/loved ones can automatically receive glucose readings and optional glucose alarms via the LibreLinkUp app as well. (Note this update is not available for the reader, only the phone apps). The Libre 3 has been approved in Canada and expected on shelves in Canada in 2024. Features of the Libre 3 include a smaller sensor, improved accuracy, and an easier one-piece applicator.
The DEXCOM continuous glucose monitor has always been a real time continuous CGM, meaning that it has always pushed readings continuously from the sensor to the receiver/phone. Not only does it alarm if sugar is low or high, but it also alarms if sugar is on its way to going low, thereby helping patients to prevent lows in the first place. The DEXCOM G6 can be used as a stand alone device, and can also be used in conjunction with the Tandem insulin pump to automatically adjust basal insulin and deliver correction boluses based on predictive blood sugars from the sensor. The DEXCOM G7 is approved in Canada and is now available in Canadian pharmacies. Improvements in the G7 include a smaller sensor that is easier to apply; a 12 hour grace period to extend use when a sensor needs changing (which is every 10 days); delaying the first high sugar reading alarm (to avoid alarms in cases such as when sugar is high only briefly before the insulin’s effect sets in); and the ability to silence alarms for up to 6 hours as an alternative to shutting one’s phone off entirely for situations like weddings, funerals, presentations and so forth (shutting off the phone entirely being a much more dangerous alternative). It also features a shorter 30 minute sensor warm up period. The DEXCOM G7 is approved for use in pregnancy. Both DEXCOM G6 and G7 continue to feature the Follow app for caregivers/loved ones to view blood sugars and receive notifications for high and low alarms. The G7 is not yet approved for use with the insulin pump.
The Medtronic CGM is another real time CGM that pushes data out continuously to the app or receiver. It is used in conjunction with the Medtronic insulin pump to automatically adjust basal insulin in response to blood sugars. It can also be used with the stand alone Guardian transmitter’s receiver, or with an app on a smartphone. The Guardian 4 is now approved in Canada, though not yet on shelves. It does not require calibrations (vs the Guardian 3 which does), though a finger prick is required to get each sensor started. The Guardian 4 is only for use with the pump (it is not approved as a stand alone system).
A special thanks to my amazing diabetes educator Anita Dobson for her support in this blog post!
Disclaimer: I receive honoraria as a continuing medical education speaker and consultant from the makers of the Freestyle Libre (Abbott), Dexcom, and Medtronic.
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