Issues with new sensors on guardian sensor

Hey guys, I’ve been having a lot of issues with new sensors. I’m using the Medtronic Guardian sensor. I’m new to CGMs so please feel free to point out the obvious. I’ve used a pump for over 10 years, but this is a new ball game to me.

The problem I’ve been having is that I’ll connect the receiver to the pump, hook up the new sensor to the receiver, then my pump will say that it’s doing the warm up process and it will take up to two hours. Within that two hour period it tells me that the sensor has expired and to insert a new sensor. I’ve checked the sensor and it says the sites are still good.

How can the new site be “expired” if it’s brand new? Is there something missing here?

Thus far to fix the problem I put the receiver back on the charger, pull it off the charger when finished charging, reconnect it to the pump and then reconnect the receiver to the still new, freshly inserted site. I have had to do this two or three times which takes up to five hours of waiting time. I feel like I’m either missing something in the process, I’ve got potentially bad hardware, or this is big joke for how expensive these units cost. Any tips or ideas would be helpful. Thanks in advance.

Have you tried calling Medtronic support?

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I second this. If nothing else, they can replace whatever turns out to be not working.

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You keep writing “receiver”. I think you mean transmitter

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You are correct. Thanks for the clarification.

Thanks for everyone’s help. I was able to call support and get through this time. I made a very foolish mistake. The problem was when I would go to setup a new site I was selecting “reconnect sensor” instead of “start a new sensor”. I had misunderstood the sensor to be the transmitter. Mistakenly, this led me to believe I should be selecting reconnect sensor because the transmitter is kept longer term.

According to my pumps logs I was ‘reusing’ the same site for about three weeks even though I had changed it after 6 days of use over that time period. ha ha.

Again thank you all for your help. mohe001, that video has been helpful. I’ve watched that one and similar others several times. Sometimes I feel like getting clear support info off Metronic’s website is difficult.

I really appreciate how supportive and awesome the community is here. I think most other forums often are filled with opinionated, uninformed, childish snarky comments. I’ve never seen that here and it’s really refreshing. I really appreciate this forum.


No problemo! Glad you’ve gotten it sorted out.

I’m also new to the Guardian sensors. Another problem that I had was calibrating with every fingerstick which was messing things up. Is there a phone app that would allow for me to see the cgm glucose on my phone?

There is not a phone app. My advice, is that if you are unsure, do not calibrate. You Ina manually calibrate if you need to do so after you complete the bolus. Generally speaking, you should calibrate on a fixed schedule. I do mine overnight, first thing int he morning, id afternoon and bed time. Others do morning, noon, evening and bedtime. still others run a schedule of no more than 3 per day or even 2. The key I think is to be consistent but no more than 4 times per day.

Note: I am a Medtronic ambassador. My opinions are my own. They did not pay me to say nice things about Medtronic devices or the company. OK, they sent me a shirt and a cup but even I am more expensive than that.

3 times a day seems to be the magic number
The first day of a sensor seems to be a little weird, but after that I only have about a 5-6 point difference between the fingerstick and cgm reading. I was on the Medtronic 508 when it first came out and had been in mdi for a long time, but I was having a really hard time dealing with dawn phenomenon and just the changing insulin needs in general. I enjoy the cgm and being able to see the trend of what my glucose is doing and make a decision based on that instead of just one fingerstick reading. This is my first cgm experience, so it’s been a little bit of a learning curve.