Wildly Inaccurate Medtronic Guardian CGM

Sorry, you are right, It has been awhile. I read the rest of the replies. I hope the letter from your Doc provides the medical necessity you need. Beware Medtronic is growing and taking over other companies. I had an Animas vibe pump and Medtronic bought them and stopped producing the supplies. I am sure they did this to force everyone to switch to one of their pump/CGM options. I chose to rent instead.

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@T1D40yr thank you! That is a super helpful note and I will make sure my doc includes something to that extent in her medical necessity letter.

@Casey2 thanks for the note. I’m definitely not interested in a pump at this time. The tslim wouldn’t be covered anyway, but I also just can’t make a pump work with playing rugby- too much time disconnected each day.
But I agree on MT buying things out. They just announced they’re buying Companion Medical, creator of the InPen, which I currently use. I am really excited for the integration of MT’s Sugar IQ app with IBM Watson and the InPen app because it could mean some really cool features for those on MDI. But, it’s ultimately unfortunate because it will mean that the InPen will only be compatible with those using MT’s CGM, whereas it was previous compatible with the Libre, Dex, and Eversense too. And, it’ll likely mean a large price increase. Both of those concerns are opposite of Companion Medical’s goal with the InPen in its creation, so it’s sad to see money win again and not the patients. Maybe they won’t screw us over, but my gut says otherwise.

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I’m sure that you know how much our state is doing to help us, at a legislative issue, with all this procedural difficulty. We got people down there. I think its wrong that you can’t get access to industry standard, functioning tech. I’m sort with @Jay6, in that you should give 'em hell if they dont approve a Dex. You play rugby - your a hellcat, and they deserve it. You live in a state full of ‘rabble rouzers,’ lol. The Mayo has your back down at the capitol. Even if you don’t see them, they are there - behind the scenes. https://www.youtube.com/watch?v=9XSIQSfYbC8
MT is a gold digger, walking a fine legal line of market fixing. We need functioning markets to survive. https://www.youtube.com/watch?v=6vwNcNOTVzY


Thanks again to everyone for the suggestions. It’s honestly just an anxiety reliever to know I’ve tried everything you all can think of too.
MT sent me a new transmitter to try and while I’ve had bouts of accurate readings and trend lines in the beginning, which got my itching with hope, I’ve since had 15-45% off readings and inaccurate trend lines- which I know because I took Bg readings every 5 mins the CGM updated for some periods of time. For the most part, it’s consistently off by 15-30% and is always 20 mins behind, so I at least have that knowledge. But I have an endo Appt in two weeks and will be asking for a medical necessity for Dexcom at that time. If I can’t get that approved despite best efforts, I’ll be getting a libre!
Thanks again everyone.

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I just saw this thread now and so I don’t have anything useful to add other than to say that I’ve had this issue too. Ultimately I gave up - I have a 670G MT and use it as a pump only, which seems like a real waste.

I used the CGM for a while but had wildly inaccurate readings and trends, as well as sensors not working well before their expiration date. I had a MT trainer come out, called the helpline several times, tried different sites, worked with the CDE at my doctor’s office (who loves MT), but to no avail. Eventually the trainer told me that the sensors don’t work for everyone. Helpful.

I dislike MT as a company for a variety of reasons that I will not go into here, but I really wanted this CGM to work. I really want to get a Dexcom/different pump, but have the same insurance issue. I will also have to work with my Dr’s office to get a letter of medical necessity.

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@Brianna1 no worries, it’s only a week old or so and I JUST told my MT trainer that I was giving up. She honestly didn’t have much to say other than she understands why I’m frustrated and going this route. Unfortunately, my endo Appt isn’t for two weeks, but I’ve got another two sensors so I’m just lumping thru until then with the MT. Unfortunately, it likely means I’ll be purchasing another set of sensors because I’m sure the process for medical necessity isn’t quick, and some data is better than no data? Idk, I’m not sure on that point yet, but I think it’s better than nothing right now.
I just finished a bike ride and am supposedly trending slightly down, one arrow, and yet my SG numbers were ever so slightly increasing, 94, 97, 98. My actual BG reading was 134, 10 mins prior. So yeah, clearly not right, haha.
Anywho, it’s honestly just really relieving to know others have gone thru the same thing. I felt like everyone I heard from outside of this forum was saying it was just me and I was in the wrong. My anxiety from it was they the roof, and so so have my BGs recently from the stress.
Anywho, it really sucks to know you had to give up, but I really appreciate you commenting and knowing I’m not the only one! Best of luck to you with the insurance! If I get any helpful tips along the way, I’ll be sure to let you know.

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I recently started on the 770 and the guardian3 sensors. I was using a 630g with a dexcom g6 prior. I have only used 1 sensor and at first the numbers were accurate as I was wearing a dexcom at the same time. The first 2 nights were okay as I didn’t get woken up in the night for a calibration or anything like that. About the 3rd night I was getting low alerts below 5.0 when dexcom said I was 6.3. I do a blood test when it says I am less than 5.0. My findings are that dexcom is always close to the fingerstick. It did that the next night too. This morning around 3am the sensor failed. Ughhhh! I am willing to go a little longer to make this system work for me. If it doesn’t I might have to go back to my old ways of treating my diabetes. Eating when a low occurs and exercising when a high happens. The pump is as good as the cgm numbers and if the numbers are inaccurate what’s the use!!!


If you are not already use the Medtronic sensor on your arm. I get better results on that location.


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

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I wouldn’t wear it anywhere else. I know what my problem was. The number I used to calibrate was too far from the sensor number. It has been accurate so far. I will be glad when the zeus sensor becomes available. Calibration only on the first day. Won’t that be nice?:slightly_smiling_face::+1:

I am so excited for the Zues sensor as well. I am hoping for 2021.

Just making sure blood glucose calibration isn’t too far from sensor reading seems like a small feat compared to micromanaging this condition. I just started automode this morning and so far it looks great. It has controlled my dawn phenomenon this morning.:slightly_smiling_face::+1:

Your blood readings and cgm readings will never Never be totally synced since they test different fluids.
It takes glucose about 5 min to move from blood to interstitial fluid and back again.
So there is always a delay. That delay is somehow built into the algorithm.

In the old days of dexcom, you calibrated and the calibration wasn’t applied until 5 min later.