Dexcom and/or Tandem - whom to call?

I use a Dexcom G6 cgm with the Tandem X2 pump. This morning my cgm sensor gave a “sensor error” on the phone app. The app message said to wait 3 hours before calling Dexcom to give the sensor a chance to come back online with readings.

I waited 3 hours, the sensor did not come back up with readings, so I called Dexcom customer service. I happened to get someone who must have had a bad day because he growled at me saying “The people who have Dexcom and also have the Tandem X2 pump are supposed to call Tandem for their sensor/pump problems.” Oh…Okay, I did not know that. So I called Tandem and that guy was also very grumpy and told me “I am trained to troubleshoot pump problems, not sensor problems, call Dexcom.”

So, I am left hanging so to speak, my pump has been suspended for over 4 hours, my BG is over 200 and I did what I should have done much earlier. I pulled the sensor, and put in a new one. By then my numbers are in the 200s and I am struggling to get them down. I went for a walk hoping exercise would help. Can anyone share what I was supposed to do when having a sensor error? This sensor was only 3 days old and all of a sudden it just went down, not working. Also, when you have a high number like I do, how can we know how much extra insulin to give ourselves? I already put in a new infusion site and have checked my BG a number of times.

Tandem handles everything sensor related after warmup. You call Dexcom if it’s something physical, like the applicator failed or the sensor just fell off. The Tandem person was way out of line and should be reported. If you call tech support back, they’ll be able to look up whoever the previous rep was. Tandem’s tech support is usually awesome, but they’ve got a lot of new hires because they’re growing so rapidly. If you call back you’re pretty much guaranteed a better experience. You might not have to call back, though.

What does the pump show? Did it give you an error code, does it show a missed signal symbol, or does it show 3 dashes “- - -” where the BG reading should be?

If it’s the latter, the 3 dashes, and you’ve had it for a total of at least 3 hours over the last 24, then it qualifies as a “failed sensor”. You can go ahead and insert a new sensor right now before you do anything else. You don’t have to wait for tech support to instruct you to do so. The 3 hour rule is pretty common knowledge, at least after the first bad sensor experience, and they don’t expect us to wait any longer than that.

If you’re situated for supplies, you can go ahead and call back whenever it’s convenient. Or you can just fill out the online sensor replacement request form and not call at all. The online form won’t address the issue with one of the reps disrespecting you, though. Tandem puts a lot of stock in maintaining their patient base so they want to renew contracts and stay with them, and they really want bad rep experiences reported.

If you’ve got the 3 dashes for 3 hours thing, you can disregard the instruction to only use that form if the pump displays the words “sensor failed”. (The 3 dashes are common, I’ve never once heard of anyone seeing the “sensor failed” error message.)
Like I said, this qualifies as a failure, and the tech support people will instruct you to use the web form for these issues.

Edit:. If you do call tech support back, babe sure you select the option for sensor issues in the call tree. It sounds like you went to the pump side of tech support, not sensor side, last time… Through in my experience, the techs are cross-trained in all issues.


I was not aware that Tandem handles everything sensor related after warmup. The sensor that failed gave me a “sensor error” on the T-connect app on the phone. The “sensor-error” also said to wait 3 hours while the sensor tried reconnecting again. During that time I did not make any calibrations, corrections or any kind of action. I stupidly just waited. Then when I tried Dexcom, I waited some more in their phone queue, they switched me to Tandem where I again waited in the phone queue. All totaled, I waited almost 1-1/2 hrs in the phone queues. By then my blood glucose was over 200. I should have been smart, I was NOT. All I saw on the pump was a red screen because the pump had suspended. I saw only the - - - on the screen where glucose numbers normally are seen.

When I called Dexcom, it was them that transferred me to Tandem and I did choose the ‘sensor’ option to get technical support. All in all it was not my day obviously. Things might have gone better if I had been more aware of whom to call.

I’m not sure what I would have done in that situation. But as you pointed out that your pump was suspended, I think I would have first copied down as much info about the “sensor error” as I could and then cleared the pump so that it was operating again albeit manually without CGM data.

What I would have a problem with is how the pump would ever reconnect with the sensor while it was suspended. Maybe the software is actually smart enough to do that, but I doubt it. Having written some software decades ago, I always expect software to be dumb, not smart. It’s just hard to write good software that is also smart. Not impossible, but, in my opinion, less likely.

And then they go and send out emails today that say everything changes Dec 1st, and that just about everything CGM related goes to Dexcom EXCEPT connection to pump signal loss and invalid transmitter (alert 29).

The first exception makes sense, but that second one is odd, as an invalid transmitter sounds like a hardware error. I wonder if it actually means it’s a type of Dexcom incompatible with Control-IQ, or something.


I always expected / thought that if Tandem loses input from Dexcom CGM, it reverts to its programmed basal rate. Just like during the 2 hour warmup period with new sensor. (Potentially over or underdosing you). Was I wrong? I have to wait for the next time I see that error!

Or maybe Trans ID incorrectly entered on pump.