CGMS wayyy OFF!

Yesterday I checked my blood sugar it was 307- ahh! BUT the weird thing was that my sensor said that i was 124, that is a biggg difference, does that mean its not working? has this ever happened to any of you?

Which sensor do you have? How long has it been in? Was your BG rising really fast? Did you just consume a lot of Carbs? Wht time of the day was this? What had you been doing before taking your BG?

If provide more info maybe someone can give you some hints or insight on what may be going on.

Another reason why this may happen was consuming any kind of medicine with acetaminophen in it. It will throw CGM readings WAY off:

That is good to know! No one ever told me anything about it, but it makes sense. What about for other CGMs?( I use the Medtronic one), not the Dex as was discussed in your previous blog. Is there chemistry based upon the same enzyme interactions? Very helpful info, thank you!


omg I didnt even THINK of that. I had a reading in the middle of the night last night that said I was at 307. I checked my BG meter and it said 169. But, I was sick yesterday and took 2 extra strength Tylenol.

Then this morning my Dex said I was “High” (over 400) and my meter said I was 250. I had taken 2 Tylenol this morning too.

I was just about to change my sensor site. haha. Good thing I read this!

Hi Kristen- Yes, it depends on how long it’s been since you calibrated your Dexcom with your meter. I calibrate mine every 5 hours or so. Kind of out of habit, I guess. Also, if you’ve taken anything with aspirin in it (Thanks Manny!) Or if your Dex is not in an accessible site on your abs. Your fingertip readings will change BG FIRST. So, if you’ve just ingested a ton of carbs, it might not be running thru your body yet, but it’ll show in your fingertips. Also, if your Dex is running short on battery. Or if it’s on the final day before you need to change your sensor (Day: 6) Or if you’re sleeping on your stomach- it’ll interfere with the readings transmitted to your Dex.

I use my Dex as a “trend graph” only. I still trust my body and what it’s telling me. If I feel sick but my Dex tells me I’m “fine”, then I check w my meter just to be sure.

That is a HUGE difference!

Tylenol (the one acetaminophen I’ve tried…) screws with my Medtronic CGM big time. It will go back to normal once it’s out of your system, but I’ve just stopped taking the stuff.

No one ever mentioned this to me either!!! Luckily I have TuDiabetes! Haha. You’d think the CGM trainers would tell you about it…they’d have to know…right?!

happens, yeah. Wait one hour after clearing alarm to recalibrate. If you calibrate immediately with such a differnet reading it continues to freak out. So test, treat, wait one hour & recalibrate, should get it back in line