Dexcom dropouts? Here's something to check

So others may know this already but I’ve never seen it anywhere and if it’s mentioned in the instruction manual it must be buried pretty deep. Backstory is that my most recent transmitter has been plagued with Bt dropouts, like 3-6 per day, rather than the occassional one or two per week I’m used to. But even those less frequent dropouts may have a similar cause. To wit, at least on an iPhone, when you pair up a new transmitter, the old pairing remains stored in BT settings even though one of the partners is no longer “alive” so to speak. They don’t clear automatically. So unless you manually go in and “forget” them, the old connections build up and the transmitter starts having trouble sorting through the when it does its 5-minute connect-and-send. I don’t have the software code to look at, but I’m guessing the transmitter just has limited time and resources for making the connection, so the more of this cruft you have, the more it has to sort through and the more dropouts you’re going to run into.

I suspected this might be the case because I’d built up a lot of these DexcomXX id’s in Settings -> Bluetooth on my iPhone. Five, in fact. So I figured, hey, maybe I should unpair some of those things! But there’s the rub: which are the old ones? Because you don’t want to unpair the active one, that’s going to cause a lot of problems. So how do you know? I looked at the transmitter SN but at first I didn’t see it, because the bit it uses for the BT designation is actually at the end. It was actually kind of a D’oh! moment, but it’s not that obvious, so I thought I’d share it here, maybe save someone else some aggravation. It goes like this:

Dexcom SSN: - - - - AB
Bluetooth ID: DexcomAB

So if you’re having a lot of dropouts, or even just a few, find out if you’ve got a whole stack of these in your BT settings, like

DexcomWW, etc etc

And just go in and “forget” all of 'em except that AB one.

The OTHER thing of course is just to remember to unpair your old one as part of the routine when about to pair a new one. Then this pesky Bluetooth build-up won’t happen!


Great post, and great timing!!. I will start new transmitter next week.

You can forget the, all the pair what ever one is sitting there. Because you only lose the data while ur deleting and repairing, prob won’t miss a single point

I just find that re-pairing a transmitter takes a lot more time and angst—on the app side, it’s like starting a new transmitter. So I prefer to avoid it, and Dexcom recommends against it. For dropped connections I just do the stop/start Bluetooth method, which I had been doing a LOT before finally deciding to figure this out.

BTW my other handy-dandy Dexcom tip is NOT to use the call-in line, where the wait queue is endless, but instead use the support chat feature on their website. I’ve generally found it much more responsive, though there are some limitations—only available during b’ness hours Pacific time, for instance. But since I’m on Eastern time it’s easy to be at the top of the queue in the a.m. Plus you get a record of the interaction and a support ticket #.


Ahh well the key is if you have it paired with a pump, and you clear it on your phone, your phone just picks up where you left off.
That’s why I can initiate a sensor on my pump and my phone will follow suit.
I don’t have to do it on both
Medical devices are paired differently than phones or receivers.
At least that’s what the info says. And my experience.
But there is more than one way to skin a cat.
Not that I support skinning cats.

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Yes, that’s an important clarification, thanks. I’m not using a Tandem so my Dexcom is just paired with my phone.