Dexcom G6 readings not accurate

Hey guys, I got my Dexcom G6 couple of days ago and my readings are way off when I compare it to my old school glucometer. It would say sugar level below 40 but actually it was 90 something. I calibrated it but still facing issues. I’m new to this kinda machine so I dunno if I should base my insulin dosage entirely on it.
Anyone else had this issue?

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If your readings are way off, then definitely don’t base your insulin decisions on them. Sometimes it may take a bit of time to get in sync with your blood sugar, but it sounds like that isn’t happening for you. Might be a bad placement or a bad sensor. If it stays consistently different from your blood sugar, call Dexcom and they will replace it.

The sensor does lag your blood sugar by 15 minutes, so if your blood sugar was changing rapidly that could explain it, but if your blood sugar was flat at 90 and the sensor was flat at 40 that is a reason to call Dexcom. Where did you place this one?


I got it from the CVS pharmacy. I called the tech support and they told me that the readings can be off by 30% or 30 units. I missed that part. It could be the placement I think. It’s been pretty stable for the day but it shows random drops when I know it’s not that low.
I’ve placed the unit on the right abdomen.

While it isn’t a “recommended” placement, my son has a lot of luck with the back of his arm for the placements. While it is true that they have loosened up their warranty terms, 40 reading with an actual of 90 is off by more than the 30% and I would get it replaced if it persists.

As for the random drops, does it trend down or suddenly drop straight down? Those straight down drops are usually caused by pressure for us.


Hi, @Zohairraza! Welcome. :slightly_smiling_face:

While this is true, 40 is well over a 30% difference. According to a call I made for a failed sensor replacement, the 30/30 rule goes as follows: if your blood glucose meter reads less than 70, your CGM is supposed to be within 30 points of your BG. If your blood glucose meter reads 70 or above, your CGM Is supposed to read within 30% of your BG meter, meaning your sensor should’ve read 63 or higher. I just might be the pickiest sensor person around, and I have to say I rarely have to apply these rules to anything I see. Did they give you a hard time about replacing it?? For I think they would’ve been wrong in so doing.

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You already said this. :grin:

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I say lots of stuff.

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It may seem that way to you, but your volume fails to impress. :grin:

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I see nothing wrong with being that picky when sensors cost as much as they do.


And when I depend on them for insulin delivery… Yeah, I shouldn’t be explaining myself on that. Great point. :grin:

Have you tried using a different glucose tester such as the Contour Next who h most people on pump use. It is also recommended by a lot of Endos.