Purchased Dexcom system, used to use MM, and am having all sorts of concerns!

Ok… I wore Minimed sensors for almost 2 years. I just purchased a Dexcom 7+ and the readings are ALL over the place! My current sensor has been in for 2 days. I don’t know if it’s user error or that Dexcom is not as reliable, but this is driving me crazy.

Here’s an example… I woke up this morning and Dexcom read 161. Fingerstick was 166 so I thought it would be perfect time to calibrate. Within 5 minutes, the Dexcom read 217. Did another fingerstick 1/2 hour later because the Dexcom still said in the 200’s and it was 157. Now it keeps telling me I’m below 50 and my fingersticks are in the low 100’s.

Also, when I looked at the graphs this morning, there were all these gaps. I’m assuming from being out of range. It was right next to me all night. Have any of you worn Minimed and Dexcom? What was your experience? Am I just not getting it??


I agree, something doesn’t seem right for you and this probe right now. By 2nd day I am usually down to 3 checks a day and happy with the D7 tracking well to the finger stick results. 1st day I normally check a lot if I can, and of course it is implied that I enter the data whenever I finger stick so that the meter can use the data too.

I’ve not used the MM but have been on the D7 (not + yet) since Dec 08. The 1st couple sensors flaked out after a couple days and self requested to be replaced. Called the 800 support line after hours each time and was “sent” a replacement. The 2nd replacement wasn’t sent (didn’t get the tracking email) so called during regular hours. That person had me upload my data and we talked about it. They suggested the 1st one was likely a body rejection due to be something new. The 2nd they suggested was just not in a good place and to avoid that place. At the time I also think I was sleeping more on that side. I’ve since trained myself to mostly avoid sleeping on that side. None the less this week I moved the probe further around my side towards my back a few degrees but the darn thing is either a marginal probe or it just doesn’t like this location. Otherwise I’ve been able to frequently get 9-11 days usage with good correlation to the finger stick results.

I’ve found that I get gaps when I have the transmitter connected to the USB upload cord so I try to remember to disconnect the USB ASAP after upload and view is completed. I also get more when I am charging the battery at night even when keeping the device right beside me in bed. And I get gaps when sleeping on the probe.

So my initial ideas are:

  1. Call Dexcom and see if they have any advise. If they don’t suggest replacing it and send you a new one then ask them to upload your data and eyeball what’s going on. Ideally you want them to suggest they send you a replacement and for you to try a new probe. My only concern here is that the people on call over the weekend might be more in hurry to get off the phone, I mean I would be, maybe they will quickly opt to send you a new one, follow-up if you don’t get the tracking email by Monday noon. If no luck with support this weekend then try to tough it out until Monday and see if you get a good support line person to eyeball the data and make suggestions.

  2. Ditch the current probe yourself without getting them to replace it for free which means you can get on with a new probe sooner. Again, it seems like my 1st 2 didn’t work that well. The 3rd I got 10 days on. I’ve almost always exceeded the 7 days but YMMV.

  3. Being an ex-MM CGMer I would guess that you do your best to get a “level” BS period for about the initial 4hrs, in the 90-130 range if possible when inserting and calibrating it. I’ve seen this type of thing recommended with the MM version but not the D7 version, but it seems to make sense to me. Ideally get into range and leveling-ish for an hr, insert and calibrate for 2 hrs, then let it stay stable for another hr. At least certainly do your best to avoid being high or low if you can.

Good luck!

You can try doing a shutdown, wait a couple of minutes, and then restart. With a new sensor that is acting up like you describe, this has worked for me. I also have had the best luck when calibrating when the arrow is straight. If it is pointed up or down at all then I don’t put a BG in, I wait. Also when my Dex jumps high like yours did this morning compared to your actual BG, I calibrate 2 to 3 times in a row using the same BG. For some reason this seems to make the Dex read more accurately again for me.

As far as the little gaps, I get them when I lay funny on the sensor. So since I always sleep 99.9% of the night on my left side, I put the sensor on the right side of my body. Then if I get gaps it is only for 5 to 10 minutes at a time when I must be laying funny.

Definitely call DexCom and let them upload your data. I have been using this for about 2 months now and I finally feel like I am getting the hang of it! I usually get 13 to 14 days on a sensor before the readings get wonky.

I use the MM CGM, but when jsut liek this happens to me, I always think it might be HAMMER time. Oh I know its not hammer time, but wouldnt that be fun once in awhile?

rick phillips