I’ve heard a few people saying that new transmitters have firmware that allows 3 hrs of data to be synced once reconnected via Bluetooth. Can anyone confirm this personally? I believe this is just for the official Dexcom app only and not xDrip (yet).
Feedback is welcome.
Yes. We have seen it happen to us several times. We lose signal for a long time, then get all the data back after the fact when we get the signal again.
I can’t say if the max is 3 hours. It definitely is more than 2 hours from personal experience.
I was surprised by that happening, as I was not aware of the new feature.
Yes this seems to be the case, although I only see it happening with the phone app, not with the receiver, which I don’t really understand
It doesn’t work with our current transmitter–so hopefully our new one has this capability.
Do we know for sure it is actual data being filled in and not extrapolation? I would hope so, but just wondering…
My iPhone is connected to our sons transmitter (if within range). When I get home from work I have noticed this myself but now I understand why it was backfilling data on my iPhone.
Yes I’m pretty sure… e.g. last night I turned my phone completely off before exercising because I didn’t want it to record the exercise trends any and didn’t turn it back on until my bg was back to normal but when I turned it on it back filled the entire history instead of just the essentially strait line it would have if it had just extrapolated
To be clear – it does not work 100% of the time, in the sense that we still have gaps – but I think that, when we have gaps, it means we really got no data at the transmitter. I have not checked Clarity to prove this assumption.
In other words, it probably does work 100% of the time 
The backfill capability is with the G5 v1.2 transmitter. Whether the transmitter is capable of this or not can be deduced from the transmitter serial number and Dexcom Customer Support. However the result should be obvious on either the Apple iOS app or the (newly released) Android app.
Note that the Dexcom Receiver does NOT include the capability to receive the backfill data. And to confirm, this is NOT extrapolation (or interpolation). This is backfill of actual data. The G5 v1.2 transmitter stores 3 hours of data within the transmitter and will allow a compatible receiver to access this data (ie - Apple iOS or Android) Dexcom G5 Mobile App.