The Best CGM/Flash? compare sensor glucose systems

Sensor-based glucose monitoring systems (CGM & Flash) can make your diabetes-care efforts so much more effective! But which one is best for your family? This side-by-side comparison of the features, function and cost of all of the sensor-based systems currently available in Canada (Dexcom, Libre and Medtronic) is clear, comprehensive and updated. We look at the features that are important to real sensor-users and their families (like us!), to help you find the technology that best meets your individual needs and preferences.

There are three companies providing CGM and Flash systems in Canada:

(in alphabetical order)

  • Abbott Diabetes Care:
    • Freestyle Libre 2
  • Dexcom:
    • G7 CGM (Continuous Glucose Monitor) stand-alone system, and
    • G7 CGM integrated with Tandem t:slim insulin pump - with Basal-IQ™ or Control-IQ™ technology
  • Medtronic:
    • Minimed 780G Hybrid Closed Loop integrated Insulin Pump + CGM System
    • Minimed 770G For Kids Hybrid Closed Loop integrated Insulin Pump + CGM System
Libre 2 Dexcom G7 Medtronic Minimed
770G / 780G 		Medtronic
Guardian Connect
What kind of glucose monitoring system is it... Continuous or Flash? Flash (data visible only if sensor is scanned)

Note: There are after-factory add-ons to turn Flash into CGM, but these are not made by Abbott, and are not approved by Health Canada.) 		Continuous Data Visibility Continuous Data Visibility Continuous Data Visibility
Stand-alone vs Integrated:
Can I use it with an insulin pump?
Can I use it if I'm on injections and don't want to use an insulin pump? 		Stand-alone Flash
(suitable for those on injections, or those using a separate insulin pump) 		Stand-alone CGM (suitable for those on injections, or those using a separate insulin pump)
OR
Integrated Insulin Pump + CGM System when used with Tandem t:slim Basal-IQ
OR
Hybrid Closed-Loop system (automatically adjust basal insulin up or down based on glucose readings) when used with Tandem t:slim Control‑IQ
(Note: t:slim pump is sold separately, by a different company, Tandem.) 		Integrated Insulin Pump + CGM System.
Also note: 770G/780G are Hybrid Closed-Loop systems when used in Auto Mode (automatically adjust basal insulin up or down based on glucose readings) 		Stand-alone CGM (suitable for those on injections, or those using a separate insulin pump)
Approved Populations:
What ages can use CGM/Flash?
Can I get one for my child? 		Health Canada has approved
Libre 2 for ages 4+ with diabetes 		Health Canada has approved the Dexcom G6 for Pediatric (Children age 2+) and Adult populations. Health Canada has approved…
770G for ages 2+ with T1D;
780G for those age 7+ with T1D, with minimum TDD of 8 units of insulin; 		Health Canada has approved the Medtronic Guardian for Pediatric and Adult populations.
Do I need a prescription? No. Any adult can order the system online without a prescription.

BUT a prescription/letter from a medical professional may be required for insurance coverage. 		Not exactly.
A prescription or Letter of Medical Necessity is not required by Dexcom. BUT a Letter of Medical Necessity from a medical professional may be required for insurance coverage.

When used with a pump, Training for Basal-IQ and Control-IQ is required (and a letter from your doctor may be required from Tandem to purchase the insulin pump). 		770G, 780G: Yes, a letter of medical necessity (prescription) is required, plus training by a diabetes educator to use Auto Mode safely. No. Anyone can order the system online without a prescription.
BUT a Letter of Medical Necessity from your doctor may be required for insurance coverage.
Accuracy:
Can I trust the glucose sensor?
How accurate are the readings? 		Overall Accuracy (MARD*):
Libre 2: 9.2% (6) (improved accuracy over Libre); Libre 11.4%1 		Overall Accuracy G6 (MARD*):
7.7% pediatric2
9.8% adult2 		Overall Accuracy (MARD*) for older model 670G (data for 780G not available):
11.2% for Adolescents;
10.0% for Adults5 		Overall Accuracy (MARD*):
As 670G
Do I still have to poke my finger? Rarely for Libre 2.
You can make treatment decisions (treat lows, correct for highs) based on the sensor glucose reading. 		Rarely...
G6 is approved to replace fingerstick checks for treatment decisions (you can treat lows and deliver insulin to correct highs based only on the Dexcom reading) BUT a fingerstick meter value is still recommended when sensor data and symptoms don’t match, or when a glucose reading is not available. 		Yes...
It's recommended to confirm glucose with a BG meter before treating lows or delivering insulin to correct highs, when sensor data and symptoms don’t match. 		Yes...
It's recommended to confirm glucose with a BG meter before treating lows or delivering insulin to correct highs, when sensor data and symptoms don’t match.
Calibration:
Should I enter independent fingerstick values to calibrate the system? 		No (System doesn't allow for calibration.) Optional. G6 comes factory-calibrated, so you’re not required to enter fingerstick calibrations, but system allows calibration if needed to improve accuracy of readings. Yes, calibrate once in the first 2 hours, then 2/day (up to 4 if the system asks for a BG recheck) Yes, calibrate once in the first 2 hours, then calibrate 2/day
Water Resistance:
Can I wear the sensor in the bath, shower, swimming pool, etc?

Also SEE NOTE on water resistance BELOW 		Sensor is IP27 water resistant: can withstand immersion in 1 metre of water for up to 30 minutes Transmitter:
IP28 waterproof (Protected against immersion in up to 2.4 metres of water for 24 hours)

(Note that t:slim pump portion of the integrated system is NOT waterproof; you can bathe with the sensor/ transmitter, but NOT with the pump/receiver) 		Pump/CGM Receiver: waterproof, with IPX8 Rating (guaranteed for submersion of up to 3.6m for 24 hours)

Transmitters (Guardian Link and Guardian Link 3): guaranteed for submersion up to 2.4m for 30 mins. 		Transmitters (Guardian Link and Guardian Link 3):
guaranteed for submersion up to 2.4m for 30 mins.
SENSOR Libre 2 Dexcom G7 Medtronic Minimed
770G/780G 		Medtronic
Guardian Connect
Sensor Life:
How long does a sensor last before I have to swap it for a new one? 		14 days 10 days (Guardian Sensor 3): 7 days Guardian Sensor 3: 7 days
Approved Sensor Sites:
Where on my body can I put a sensor?

Also SEE NOTE on approved sites below 		Back of Upper Arm Abdomen
Back of the arm
Upper Buttocks (age 2-6 years)
 		Children (age 7-13): Abdomen, upper buttocks
Adults (age 14+): abdomen, back of arm 		Children (age 7-13): Abdomen, upper buttocks
Adults (age 14+): abdomen, back of arm
Warm-Up Period:
How long do I have to wait for data after I insert a sensor? 		60 minutes 30 mins 40 min to 2 hr warm-up before 1st calibration, plus 15 mins after 1st calibration before receiving glucose readings 40 min to 2 hr warm-up before 1st calibration, plus 15 mins after 1st calibration before receiving glucose readings
TRANSMITTER Libre 2 Dexcom G7 Medtronic Minimed
770G/780G 		Medtronic
Guardian Connect
Transmitter Memory:
How much back-data does the transmitter store?

That is, how long can the transmitter and receiver be out of communication before data is lost? 		8-hr
Transmitter Memory
(Transmitter holds 8 hrs of data, which will be back-filled to Reader when Sensor pod is scanned) 		Using a Smart Device:
3-hr
Transmitter Memory
(up to 3 hours of missed glucose readings will be back-filled to your smart device)

Using a Dexcom Receiver:
Zero back-fill of data 		10-hr
Transmitter Memory
(Guardian Link 3 holds 10 hrs of data); data gap appears only if transmitter and insulin pump are apart for more than 10 hrs) 		10-hr
Transmitter Memory
(Guardian Link 3 holds 10 hrs of data); data gap appears only if transmitter and insulin pump are apart for more than 10 hrs)
Transmitter warranty:
How long do the transmitters last? 		N/A
Transmitter is built into the sensor, so is replaced with each new sensor application 		N/A
Transmitter is built into the sensor, so is replaced with each new sensor application 		1 year from date of purchase (but anecdotally, most last much longer if they are regularly charged/discharged) 1 year from date of purchase (but anecdotally, most last much longer if they are regularly charged/discharged)
Transmitter Batteries:
What kind of batteries do the transmitters use? Can I replace them when they die? 		N/A
(Battery is non-replaceable and non-rechargeable but is replaced every 14 days with each new sensor, so battery life is a moot point) 		N/A Rechargeable
Non-replaceable
(charger is supplied - when it can no longer take a charge, you replace the transmitter) 		Rechargeable
Non-replaceable
(charger is supplied - when it can no longer take a charge, you replace the transmitter)

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RECEIVER Libre 2 Dexcom G7 Medtronic Minimed
770G/780G 		Medtronic
Guardian Connect
Receiver Options:
What kind of receiver can I use? 		Dedicated Libre Reader with touchscreen display
OR
Smartphone with Freestyle LibreLink app

Note: no Wifi needed to scan the sensor with your phone; Libre 2 uses Bluetooth, Libre uses Near-Field Communication (NFC) 		Smart Phone
(iOS, Android) with App; Smart watch; Optional Dedicated Dexcom Receiver with touchscreen display 		CGM Receiver is integrated into the insulin pump – CGM data is displayed on the pump screen.
770G/780G has smartphone connectivity. 		Your Apple Smart Phone with App acts as a receiver (potential for up to 5 users)
Remote Viewing:
Is this information sharable with others?

Can I see my son's glucose readings when he's over at a friend's house, or my daughter's glucose when she's out on the soccer field, or my husband's data when he's traveling for work? 		Yes, with FreeStyle LibreLink app
(compatible with Bluetooth or NFC-enabled iPhone 7 or higher) + LibreLinkUp app for caregivers (data shared automatically with up to 20 people)
AND
LibreView cloud-based diabetes management system 		Yes, only when using a smart device as the receiver (with the Share app on the PWD's smart device, plus the Follow app on the follower's smart device) Yes, when using a smart device as a secondary receiver. Yes, when using a smart device as a secondary receiver, through CareLink™ Connect platform
Range:
How close does the sensor/transmitter have to be to the receiver? 		To scan, hold reader within 4 cm (1.5 inches) of the sensor Maximum Range is 6 metres Maximum Range is 2 metres Maximum Range is 2 metres
Receiver Life/Warranty:
How long does the receiver last? 		Average service life: 3 years of typical use 1-year warranty for dedicated Dexcom receiver 4-year warranty (as per insulin pump/CGM system warranty) plus 1 additional year under certain funding circumstances Your smart device is the receiver; warranty depends on the device manufacturer.
Receiver Battery:
What kind of batteries do the receivers use? Can I replace them when they die? 		Libre 2 Reader:
non-replaceable;
re-chargeable
(7-day battery life between charges with typical use)

Smartphone as Receiver: battery life varies. 		Dexcom Receiver:
non-replaceable;
re-chargeable
(need to charge it every about 3‑6 days)

Smart Phone or Watch as Receiver: battery life varies. 		1-AA for pump/CGM system (Lithium is recommended; also accepts alkaline or fully‑charged NIMH rechargeable) Your smart device is the receiver; battery life varies.
Glucose Trends:
How do I know whether my glucose is steady, rising or falling? 		5 trend arrows
(2 rise/fall levels):
→
OR
↗ to ↑
OR
↘ to ↓ 		7 trend arrows
(3 rise/fall levels):
→
OR
↗ to↑ to ↑↑
OR
↘ to ↓ to ↓↓ 		In Manual Mode:
9 Trend Arrows
as in Guardian Connect (next column)

In Auto Mode:
Trend arrows are not central, as the system is most effective when insulin is adjusted automatically. So only ↑ or ↓ are displayed. 		9 trend arrows
(4 rise/fall levels):
→
OR
↗ to↑ to ↑↑ to ↑↑↑
OR
↘ to ↓ to ↓↓ to ↓↓↓
Low/High Glucose Alarm and Alerts:
Will it notify me when my glucose is low (or high)? 		Libre 2: YES. Transmitter communicates every minute with the receiver via Bluetooth, you will receive alert/alarm notifications even without scanning. Yes.
Low Alert limits are adjustable from 3.3 to 5.5 mmol/L.
High Alert limits are adjustable from 6.7 to 22.2 mmol/L.
PLUS
Fixed Low Alarm goes off when glucose is under 3.1 mmol/L, cannot be adjusted, cannot be turned off 		Yes for all models.

770G/780G Auto Mode:
Low Alert limits are adjustable from 2.8 to 5.0 mmol/L.
High Alert limits are adjustable from 5.6 to 22.2 mmol/L.
Plus these other alerts: Auto Mode Exit, Auto Mode Off, BG Required, Calibration Required 		Yes.
Low Alert limits are adjustable from 3.2 to 5.0 mmol/L.
High Alert limits are adjustable from 5.6 to 22.2 mmol/L.
Alert Before Low/High:
Will it notify me when my glucose is about to go low (or high)? 		No Yes - predictive Urgent Low
Soon alert 		Toggleable alert before low, and mandatory alert on low both in and out of Auto Mode Alerts 10-60 mins before a low (or high) is predicted based on current glucose reading plus trend information; can be turned on and off 8 different times (ex. overnight) throughout the day
Rate of Change Alerts:
Will it notify me when my glucose is changing rapidly? 		No Yes, with adjustable Rise Alert / Fall Alert. No Rise Alert notifies you if your glucose is rising rapidly; there is no Fall Alert per se - this function is served by the Alert Before Low
Will it turn off my insulin when my glucose is low? N/A
(not integrated with insulin pump) 		N/A
for stand-alone system

Yes
for integrated system with Tandem t:slim X2 with Basal‑IQ or Control‑IQ 		Yes.
Suspend on Low feature.
See Pump Comparison Chart 		N/A
(not integrated with insulin pump)
Will it turn off my insulin when it predicts my glucose is headed for a low? N/A
(not integrated with insulin pump) 		N/A
for stand-alone system

Yes
for t:slim X2 integration with Basal-IQ or Control-IQ
 		Yes.
Suspend Before Low feature

See Pump Comparison Chart 		N/A
(not integrated with insulin pump)
Alert Volume:
Can I make the alerts louder or softer? 		Yes. Adjustable: 4 levels, from vibrate to attentive Adjustable: 5 audio levels plus vibrate Adjustable: from vibrate through different volume levels

Notes:

MARD = Mean Absolute Relative Difference, a measure of error (as an average %).
MARD represents the difference between the patient’s CGM readings and the glucose values obtained from a lab analyzer. A lower value means values are closer to the lab reference values (i.e. sensor is more accurate).

These sites are officially "approved" because the company has invested the time and money to conduct a study on the effectiveness and safety of the system on that body part. This doesn't mean it can't be used on other sites, it just means it hasn't been tested on other areas, and its safety and effectiveness when used on alternate sites cannot be guaranteed by the manufacturer. At your own discretion (and perhaps guided by the personal experiences of other users), you can experiment with other insertion sites, to see what works well for you.

These are the official water resistance ratings, however, many people wear their sensors in the water for longer without problems, you just might need some additional skin prep to cover up the sensor or keep the sensor from falling off. YOUR DEVICE WARRANTY MAY DEPEND ON STRICT ADHERENCE TO THE WATER RESISTANCE RATING. If so, PLEASE FOLLOW IT CLOSELY!

 

References:

  • 1.

    Bailey, T., Bode, B. W., Christiansen, M. P., Klaff, L. J., & Alva, S. (2015). The Performance and Usability of a Factory-Calibrated Flash Glucose Monitoring System. Diabetes Technology & Therapeutics, 17(11), 787–794. http://doi.org/10.1089/dia.2014.0378

  • 2.

    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 Jun;20(6):428-433.

  • 3.

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

  • 4.

    Veeze HJ. et al Poster 136 ISPAD 2014 : Real-life performance evaluation of the New Generation Enlite™ glucose sensor in patients with Diabetes Mellitus.

  • 5.

    Garg, S. K., Weinzimer, S. A., Tamborlane, W. V., Buckingham, B. A., Bode, B. W., Bailey, T. S., Brazg, R. L., Ilany, J., Slover, R. H., Anderson, S. M., Bergenstal, R. M., Grosman, B., Roy, A., Cordero, T. L., Shin, J., Lee, S. W., … Kaufman, F. R. (2017). Glucose Outcomes with the In-Home Use of a Hybrid Closed-Loop Insulin Delivery System in Adolescents and Adults with Type 1 Diabetes. Diabetes technology & therapeutics, 19(3), 155-163.

  • 6.

     Alva S, Bailey T, Brazg R, et al. Accuracy of a 14-Day Factory-Calibrated Continuous Glucose Monitoring System With Advanced Algorithm in Pediatric and Adult Population With Diabetes. Journal of Diabetes Science and Technology. September 2020. doi:10.1177/1932296820958754

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