How do you like the Medtronic Guardian 3 sensor?



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The Guardian 3 sensor is the required CGM to use with the Medtronic 670G Insulin pump. The pump uses the readings from the sensor to automatically deliver insulin when in auto mode. It is a hybrid closed loop system.

Some people don’t like the sensor, but I’ve had pretty good success with the sensor. I always use it on the upper back/side of my arm. My husband helps me apply it there.

I tried my abdomen once and my thigh once and both times it didn’t work. Medtronic did replace the failed sensors.

It’s really, really frustrating when it doesn’t work, but most of the time I’ve had success. It is best to start in the morning because on the first day it requires more frequent calibration.

Restarting and Marinating

The Guardian 3 sensor is only supposed to last 7 days but many people re-start the same sensor and are able to extend them. I’ve just had success with extending one myself. I used it for 12 days. Then it started waking me up to calibrate, so I decided it was time to replace. (UPDATE: I’ve decided to stop extending them, because I didn’t like the uncertainty of when they would stop working. I don’t recommend extending them.)

The sensor is typically less accurate on the first day. Because of this, I started to “marinate” them by inserting the new sensor the night before I start using it, so that the first day has better accuracy. Read about my sensor change routine.

Top Tips for Improved Accuracy

  • Calibrate when in normal glucose range, when glucose is staying relatively steady.
  • Stay hydrated. Drink plenty of fluids.
  • Be aware that Acetaminophen-containing pain medicine, like Tylenol, can cause inaccuracy.

Also, always calibrate before bed, so that it lets you sleep through the night. I find them to be very accurate most of the time. Often within 10-15 points of my blood glucose reading. Sometimes spot on, or just a few points off. If it’s more than 20 points off after the first day, that’s surprising.

More on the Medtronic 670G Insulin Pump & Guardian CGM System


3 responses to “How do you like the Medtronic Guardian 3 sensor?”

  1. Mario Belec

    The Medtronic sensor is very inaccurate compare to the Dexcom G6. Very disapointing.

  2. Bill

    I have been on the Guardian G3 since May. This sensor is making me check my glucose from 2 times a day to 20 times a day and a lot of times within 15 minutes of the previous test. Average number of tests over the last 9 months is 8 tests a day. Unfortunately I have a Minimed 770G which requires you to use this sensor, in another 3 years I will definitely be looking at another brand of meter that uses the Dexcom CGM.

    1. Wow, that doesn’t seem right! I use the same sensor and only need to calibrate 2-3 times a day. Having to check again 15 mins later makes no sense! Maybe you can reach out to Medtronic about this.

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