Dexcom Surprises

calibrationThe other day was a frustrating day on the Dexcom. In the afternoon, after a luncheon I had thrown at my apartment, my Dexcom was showing me at a steady 270 mg/dl while I was working my retail job. It wasn’t coming down, which I found really odd, so I went into the back to test. I was 140 mg/dl.


So I callibrated, and all of a sudden the Dexcom alarms asking me for a blood sugar reading! But I just did one! 

The second calibration held and the Dexcom worked again.

Later that night, as I was getting ready for bed, the Dexcom showed me at a steady 117 mg/dl. Awesome, I thought. I really showed that luncheon who’s boss! But then when I tested, I rang in at 295 mg/dl! What the crap?!

When I calibrated, the Dexcom once again prompted me for another reading.

At this point I thought there was something fishy going on with my sensor. I’d had this alarm prior but I could never figure out what it was from, and so I though maybe it was a sign of a wonky sensor or a bad connection. Frustrated and not wanting to deal with bad reports from a Dexcom, I ripped out the sensor on just Day Five. Perhaps a bit premature, but it was late and I was frustrated.

The next day, I finally got around to tweeting about what had happened. Surely someone on the Internet will know! And sure enough, three people wrote me back explaining that the Dexcom will prompt you for a second blood sugar reading if the calibration reading is way off from what it currently has you at. They say that they do that because the Dexcom doesn’t want you feeding it a potentially erroneous blood sugar reading, for instance, if you had some food still on your hands.

Smart thinking, Dexcom! I totally would not have thought that it was actually a safety precaution and I had never heard of anyone saying that the Dexcom will prompt you for a second reading if your meter reading and Dexcom reading are very far apart.

Goes to show you learn something new everyday!

Do you have any technology surprises about the Dexcom or Omnipod that I should know about?

7 thoughts on “Dexcom Surprises

  1. I write a lot about technical issues/current topics with the DexCom on my blog. If you’re interested, swing on over and just pull up all the posts I’ve labeled “dexcom”.

  2. Minimed also has a lot of inaccuracies. It’s probably asking for another BG reading because of the wildly different readings it’s spitting out. (MM users get Calibration Errors.)

  3. When I started with my G4, I felt that mine wasn’t as accurate as many others were reporting. At that time I was using my Ping meter for calibrations. I was also using a Verio meter at the time. Lifescan touts it as “more accurate,” but generally it didn’t seem so to me. But ever since I started using it for all of my calibrations, my G4 is way more accurate. So take that for what it’s worth!

    • Gary Scheiner actually told me at my appointment that my current meter, the Ultra2, has the worst accuracy of all the meters. Yikes! Luckily I’ll be getting a Freestyle when I go on Omnipod and he says that’s a very good meter. Woohoo!

  4. The biggest element with accuracy is that you input a blood glucose reading only when you are —> (that’s my best horizontal arrow) level. Because our G4’s lag 15 minutes or so behind, we can never set an accurate calibration. It’s interesting to watch how the difference in how close the G4 reads after you’ve calibrated when your even/level. You’ll love the Omnipod Freestyle meter–so little blood required!

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