Dexcom Software Glitch

I can’t really call it a bug but I guess you can say it is probably just something the engineers did not think about and is something potentially dangerous.

Back in July, Dexcom replaced my receiver.  That first night, I noticed something was not right with the alarms.  I went to bed and as usual, I checked my blood sugar right before.  I had the Dex lying on the bed and had rolled over so the Dex was behind me.  It started to vibrate and because I knew what my blood sugar was, I ignored it and figured I would get it when it beeped in 5 minutes.  Instead of beeping 5 minutes later, it vibrated again.  And 5 minutes later, it vibrated again and no beeps.  I went downstairs to call Dex and while I was on hold for the tech, it started to beep.  I talked to the tech and she said just to keep an eye on it and if it happened again, call them back.

This past month, I had a couple times that it vibrated a couple times instead of beeping.  I have also had a bunch of bad sensors so last weekend, I was at the point I was just ignoring the alarms.  I was lying on the couch and had the Dex in my Spiblet.  I felt it vibe and it vibed three more times before it beeped at me.  I was supposed to call Dexcom on Monday so they could upload my data, so in the conversation about the problems with the sensors, I brought up the problem with the alarms.   The tech suggested watching the alarms and writing down anything that happened.

Shhh, don’t tell anyone I said so, but logging sometimes does help!  In the afternoon when I was sitting at my desk, instead of keeping the Dex in my Spibelt, I had it on the desk.  For those of you that don’t have a Dexcom, when the alarms go off, the screen lights up and will say, low, high, rise or fall, depending on what the alarm is for.  Dexcom has two different low alarms.  You can set what number you want as your low alert – I have my alarms set for 70.  Dexcom also has 55 set for an alarm that you cannot turn off.  When the screen lights up for a low, either 70 or 55 will be in the display depending on what your blood sugar is.  When my screen would light up, I did not acknowledge the alarms, but I wrote down what it did and what time it was so I could track what it was doing.

At 4:38, I had a regular low alarm and the Dex vibed.

At 4:43, I had a low 55 alarm and the Dex vibed again.

At 4:49, I had a regular low alarm and the Dex vibed again.

At 4:53. I had a regular low alarm and the Dex beeped at me.

So, did you figure out what happened?

When the Dex beeped, I acknowledged the alarm and was able to see what the Dex thought my blood sugar was – I was 56.  When the alarm vibed the second time, I was below 55 so the Dexcom started a new series of alarms and did not consider that it was actually my second alarm.  For the third alarm, I went above 55 again, so that started yet another series of alarms and did not take into account the previous alarms.  When it got to the fourth alarm, I was still above 55 so that time, it treated it as the second warning and beeped at me.  Since the fourth time, my blood sugar was so close to 55, if it had dropped below 55 again, it would have vibrated instead of beeping at me because it would have considered that yet another new series of alarms.  I could have easily kept going above and below that 55 line for awhile and not get any beeps.  I was awake and treating my low, but had I been asleep, I would have lost 20 minutes treating my low.

I am having some other issues with the alarms not going off, but that is whole other article and at least the mystery of the repeated vibes is solved!
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Comments

  1. Wow! Like you say the S/W needs to be tweaked – where it is able to recognise the sequence of alarm events. It seems to be getting mixed up as to when the 1st event happens – and somehow resets itself. Is that you take on it as well?

    I know with the Medtronic CGMS I had done a test trial with – I had issues with the accuracy of what my BG was when it alarmed (20 minutes delay). Do you always do a vampire blood test to confirm what your CGMS is? Just curious – as I’m sure the Dexcom has the same procedure as the MM CGMS had – but then this is 3 years ago when I gave this a go.

    • I have the same take as you Anna – it seems to be resetting itself when it goes into a different alarm category.

      Someone on the TuDiabetes Dexcom group yesterday posted a scientific explanation as to why the MM was 20 minutes behind – apparently, that came from published papers. There is something different with Dexcom that it doesn’t have that same lag. A lot of people seem to find it catches lows faster than highs.

      I still do lots of vampire tests just to double-check. I was cutting back some but then ran into a bad batch of sensors so am back to checking 18 times a day. You have to do at least two vampire sticks a day to calibrate the Dex. I like to double-check before taking insulin or if something seems out of whack.

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