In the past few days, my sensor has been losing contact with my Tandem pump for a couple+ hours every so often. I started up a new transmitter back on April 22, so I should have had about four days left as of yesterday (and I did have a little trouble a couple days before that). My sensor is mounted about three inches to the right of my navel, and my pump is on my belt on the right side, so they are less than two inches apart.
The worst time was yesterday: I was on a long hike, and found I didn’t have my Dexcom results to keep track of how I was doing. Fortunately, I’m in the habit of carrying my blood glucose meter with me in such situations, but it was a pain to have to stop every half hour and check.
So, question: is this likely to be a failing transmitter battery? I know some folks use theirs well beyond the standard 90 days, and I’ve not had one fail early in my 2+ years of using the Dexcom. Or could it be something else, perhaps even the sensor? But it seems that would just fail, and not start working again. (The sensor will need replacing in three days, probably at the same time as the transmitter; I’ll probably just replace everything and see what happens.).
Or am I missing something else, probably something obvious? I’d call Dexcom to ask about it, but every time I’m thinking of doing that, the #!&@ thing is working! So I don’t want to bother them about something which is currently working just fine. (This morning I had two short periods of non communication, but it’s working fine right now).
Thanks for any suggestions!
–Keith
@K_Hjalmar, happens to me quite often but not with every sensor. But when it happens, it seems to happen sporadically throughout the life of that sensor. That’s about 10% of sensors only. They work and then drop out and pick up again within a few minutes to maybe an hour or two. Later, I find there is no record of it in the pump as though the pump filled in the voids. I also find that happens in cases of both extreme lows as well as extreme highs. I have no clue as to what causes it. BTW, better places to put the sensors are the upper arms. When I had them on my belly, they tended to snag on clothing and get scraped off. I know that Dexcom says the belly, but that’s only because their FDA approval was for only that site and they have not tested anywhere else.
I tend to rise and fall quite fast and that might be the reason… the CGM not being able to follow as quickly.
K,
My G6 is only pairing with my cell phone, so this is not particularly relevant to your situation, but may provide reference.
My loss of signal is not infrequent, and I’ve gotten fairly adept at uninstalling the G6 app, re-installing the app, and pairing with the existing transmitter.
Yesterday when I did this – and I swear this is true – the warm-up period lasted less than two minutes! When the newly-installed app is paired, the original session start time and expiration are intact and valid! The session picks right up where it lost communication.
It’s a bit of a headache, but less stressful than trying to convince the brainwashed tech support people at Dexcom that their product or app is faulty!!!
I’ll look forward to hearing if you can re-pair you pump the way I’m able to re-pair my smart phone. 
To my knowledge, there is no way to re-pair the sensor with the t.slim pump without removing the sensor, restarting it and initiating a new session. Too much rigamarole when all one has to do is to wait it out.
That was my expectation regarding re-pairing the G6 transmitter with my smartphone, Willow4. But, as long as communication has been lost, there’s no harm done in trying.
When prompted to insert a new sensor, I just acknowledge the demand, and continue with the set-up process.
I’ve had this happen in the week before a transmitter either is scheduled to end or fails.
So I just use the phone app, not Tandem integration, but fwiw, there are a lot of things that can cause glitches with Bt connections. One is just the number of active devices you have going. Another, which is more specific to Dexcom, is that pairing a new transmitter does not automatically delete the previous one, at least in the case of the smartphone app, and you can end up with multiple expired devices still recorded in the Bt registry list. This can cause the active transmitter to glitch when it’s trying to address your receiving device. At one point when I was having a lot of dropouts, tech support had me check my registry and delete the old ones—I think I had like five expired ones in there—and it seemed to help. Not sure how this translates to a Tandem pump rather than a phone app as the receiver, but it seems worth mentioning. The other thing I’ve found is not to wait for the system to reconnect on its own, but to switch Bt off and back on in my phone settings, which seems to clear whatever the glitch is so that connection is reestablished within 5minutes—the regular transmission interval—rather than going on for 30-60 minutes or more. Again, not sure what the equivalent of that would be in Tandem pump-land.
@K_Hjalmar
I suppose the equivalent with a t.slim to @DrBB 's suggestion would be to turn off Control IQ and wait 30 seconds and then turn it back on. Will try that next time the CGM fallout occurs.
I find the whole connection thing to be weird. Sometimes I lose connection with my pump sometimes it’s my dex ap sometimes it’s my tandem ap.
One phone 2 apps and one of them loses connection.
It makes zero sense. Luckily it doesn’t happen very often.
Turning off Bluetooth and back on usually works.
If I’m losing connection to my pump it’s usually the battery going bad.