Does the Dexcom G5 (using the included receiver) do "data backfilling"?

ie, if out of range for some period of time, will the missing data “back fill” when the connection is re-established with the xmitter, similar to the Medtronic CGM?

That is my understanding, but maybe I’m thinking of the “professional” CGMs that Endos used to loan to us for a weekend.

I could be wrong because I am still using G5 transmitters that were sent to me a year ago. I have read that the newer transmitters do backfill, but I think it is only through the phone.

I guess I’ll ask Dexcom tech support next time I call.

@Dave44 - The new G5 transmitters have backfill capability up to a maximum of 3 hrs into the past. Sometimes referred to as the G5 v1.2 transmitter.
I really love this feature.

There should no longer be any Dexcom G5 Transmitters being shipped (from either Dexcom direct or a distributor) that do NOT have this feature. There is no special marking on the Transmitter box but it can be identified based on the serial number (actually Transmitter ID). And it is obvious when it works.

The newer Dex App on a Smart Device supports this functionality on the receiving end. I don’t know exactly when the app started supported this but if you just go with the current version then you know it has the support.
The Tandem t:slim X2 with the G5 update also supports the backfill capability.

The Dexcom Receivers available still do not support this, even the ones currently being shipped out direct from Dexcom.

I have not heard specifically if the newer (not yet available) Dexcom Touchscreen Receiver will have this backfill capability. I would be pretty surprised if it did NOT have it. Dexcom CEO (August 1, 2017 - Q2 Earnings Call) speaking about Medicare recipients and the new Dexcom Touchscreen Receiver:
“For Medicare right now, since we have the receiver, we continue to sell it and have it part of the system. We have a new receiver we’re launching here in the fall that will be here for the patients.”
(ie - “new receiver” would be the Touchscreen Receiver that has not yet been made available)


Thanks for all that info Tim, and thanks to everyone else for your input. I had no idea a touchscreen was in the pipeline–interesting! Glad to hear about the 3-hour backfill on the current ones.

@Dave44 - The current Dexcom Receivers do NOT support the backfill functionality.

Let me know if you have any questions.

thanks! Once I get it up and running, I’m sure I’ll have some. :slight_smile: My biggest concern is keeping the sensor/xmitter secure since I sweat so much from activities. IV3000’s couldn’t always keep my Enlites secure if I sweated excessively.

@Tim35 is correct on both points. All transmitters backfill, and the receivers don’t take advantage of it. I also love this feature.

One thing I’d add is that the “follow” iOS devices don’t always see the backfill, even when the primary phone does. But you always get it on Clarity.

I used IV3000 when I started out with the old Sof Sensors. It is completely hopeless! For Dexcom the most commonly used (and IMO best) solution is Opsite Flexfix tape + Skin Tac. there have been loads and loads of posts on this so just search the archives.

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The manual for the touchscreen receiver is available for download on Dexcom’s website, in the support section.

During a convo with Dexcom, they confirmed there is no data backfilling. What a BUMMER! I should be able to be out of range of the receiver for some period of time, and when the connection is re-established, it should fill the data in, just like the Medtronic CGM. Depending on who I speak with it dexcom, it’s either “there is backfilling” or there adamantly isn’t.

first day, this thing is crazy-accurate!!! :slight_smile:

@Dave44 - I agree with the accuracy. Although it apparently is not accurate for everybody, we also find it to be amazingly accurate. IMHO the best thing you can do in terms of “helping” it with accuracy is use the best meter you can obtain and be very particular about WHEN you choose to do the calibration. Do NOT simply calibrate it whenever it requests a calibration. The best calibrations are when you are in range of your target BG (or almost) and have a straight and level BG.

In terms of the G5 backfill functionality, I can positively and emphatically confirm that all G5 Transmitters currently shipping from Dexcom contain the backfill functionality. The current version of the Dexcom App on both Apple and Android contain the backfill functionality. The Tandem t:slim X2 pump with the G5 update also contains the backfill functionality.

The backfill functionality has the ability to go up to a maximum of 3 hours into the past.

The non-touchscreen Dexcom Receiver does not have this capability. As of recently, this is the Receiver which Dexcom has been shipping. If this is the only method you have for receiving the cgm data from your G5 transmitter than you would not have access to the backfill functionality.

It is as of yet unconfirmed whether the new touchscreen Dexcom Receiver will or will not have this functionality. Based on @Jason99 pointing out that the new touchscreen receiver manual is now available on the Dexcom website, Dexcom is apparently about ready to ship these - if they have not already started shipping. It will be interesting to find out whether or not the new touchscreen receiver contains this backfill functionality.

thanks for all that info, Tim! It would be a major bummer if I just got on the tail-end of a receiver that is about to be replaced with a better unit. Just my luck. I wonder if Dexcom has anything in place to allow us to upgrade for a nominal fee. I wouldn’t mind spending a few hundred if the new receiver is a substantial improvement of the current unit. the receiver I have is very basic. can’t scroll thru the graphs, can’t select different sounds like on the phones, I get no early warning of when a calibration is due (other than 15 minutes?). No brightness control for the screen…

@Dave44 - For any data analysis, you would most likely want to upload the data into the Dexcom Clarity or Diasend cloud applications and analyze the data there. No receiver IMHO would allow any sort of reasonable data analysis.

(Likely other cloud apps work for analyzing the Dexcom cgm data but those are two that we use and know for sure are able to upload the data from the current Dexcom Receiver.)

The brightness on the current Dexcom Receiver actually works great as a flashlight in the night for going up the stairs. Really - I use it for that. lol

With the calibration, bear in mind that you do not need to calibrate just because it “requests” the calibration. The cgm system will continue to provide numbers and in our experience, the accuracy does not suddenly decrease just if we decide NOW is not the best time for a calibration.

I often find that first thing in the morning (for us) is a good time to calibrate (whether the Dexcom is asking for it or not) and then we might have a good time in the evening and sometimes we just skip the second calibration of the day. If you DO want to see the last calibration time, this information is available to you from the menu at:
Settings ==> Device Info ==> Last Calibration
And the Dex would alert and request another calibration 12 hrs from the listed time.

Dave, why are you using the receiver over your phone? Are you on Medicare? If you are on Medicare, you will be prohibited from getting anything but the non touch screen receiver, with no option to upgrade, just like any other medical device Medicare covers.

I browsed through the user guide for the G5 w/ touchscreen receiver. It mentions using the Mobile App. Does that mean it has the features similar to the phone app?

@Jason99 - I am not sure on the touchscreen for Medicare recipients. The Dexcom CEO did appear to be strongly implying (without directly saying) that the touchscreen receiver would be sent with new orders for Medicare Recipients when it starts shipping. This is what he said below - which could be interpreted differently as well as an “intention” can turn out to not be the ultimate reality for one reason or another that was the way I read into this.

“For Medicare right now, since we have the receiver, we continue to sell it and have it part of the system. We have a new receiver we’re launching here in the fall that will be here for the patients.”

Yes, on Medicare. so the rule is no touchscreen receiver (even if i paid for it), correct?

EDIT: Now I see Tim’s reply which clouds the issue. :slight_smile:

No. That is not the rule. Let me find and cut-n-paste.

Edit. Rule cut-n-pasted with source provided.
This is the rule. Unless/until it is updated.
Now you could have three people who read this and come up with three different interpretations based on various real world scenarios. That is just the reality. Unfortunately.
"The Medicare DME Benefit excludes coverage for non-medical items, even when the items may be used to serve a medical purpose. As a result, smart devices (smart phones, tablets, personal computers, etc.) are non-covered by Medicare under this exclusion. Likewise, medical supplies used with non-covered equipment are not eligible for Medicare reimbursement."

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