Maximize Dexcom G5 Transmitter Life

Although often described as a 90 day lifespan, the Dexcom G5 Transmitter actually lasts a bit longer.

Note: This is specifically when running the Dexcom G5 Transmitter with the Dexcom Receiver, the Tandem t:slim X2 pump and/or the Dexcom G5 Mobile App.

You should be able to get a minimum of 106 days out of the transmitter and potentially 112 days.

A sensor start will only work if you can still get a full 7 days from the existing transmitter.

If the sensor is restarted on Day #106 (which is date of transmitter activation plus 105 days) then it should work and allow another 7 days on that transmitter up to Day #112.

If the sensor is restarted one day later (ie - on Day #107) than a message will be displayed indicating the transmitter needs to be replaced and the session is not allowed to be started.

The easiest way to “count days” is with MS Excel. Put the transmitter activation date in one cell. Put the number of days to add, 105 into the next cell. Add these cells together and it should result in a date which is 105 days out. (105 days out is Day #106.) Put a reminder on your calendar that this day is the last possible sensor restart for this transmitter.

Being able to run the transmitter for 112 days as opposed to the advertised 90 days results in a 25% increase.

At a minimum, you should be able to get 106 days which is almost 18% greater than advertised.


@Thomas, this is a great tip! We recently ran into this one.

I hope my day counts are not wrong !!!

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Thomas can you clarify - you say if you restart on day 106 you can go to day 113 - but I’m not sure how I get to 106. I got a warning that this is my last sensor period but I am just coming up to 89 days tomorrow when it expires. I won’t get the chance to get to 106 as it won’t let me restart it at 89 days right - or are you saying it will let me restart even if I am over 90 days ?

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It will let you restart the next sensor. But you need to time your last sensor restart before day 107 :slight_smile:

me too :slight_smile: I am now thinking that I should label the transmitter the same way as @Eric’s tip for the Pods:

I could label the transmitter with the date of Day 106 – assuming that @Thomas is counting correctly :slight_smile:

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@Robellengold - Where did you get that message? What device? What version? The message I got a few weeks back (I didn’t write it down exactly) was on both the G5 Mobile App (v 1.7.2 on iPhone) and the Dex Receiver (new - manufactured beginning of August 2017). It said something like:
Transmitter battery low. Replace in 22 days.
More or less but it specifically had the number of days and either 22 or very very close to that number.

Definitely I did not see a message as you describe which is very odd so I wonder if this is a “version” thing?

So to be more specific with the dates of our last G5 transmitter.
G5 was activated on June 20, 2017. (Don’t know the time of day.)
Last good sensor restart was on Oct 1, 2017.
Failed restart on Oct. 4, 2017.

Counting June 20 as Day #1
Sensor good restart on Oct 1 was Day #104
Failed restart on Oct 4 was Day # 107

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I didn’t write them down but I got the 22 day warning about 2wks ago. When I started the latest session it said - 'this will be your last session as you will not be able to start another session when it completes as you will have reached 90 days total use.
My calcs put me at 68 days when i got the 22 days message not 106. I could try and restart tomorrow instead of let it run out I guess on friday to see it if lets me, but I am still waiting for my replacement from dexcom !

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@Robellengold, what platform did you get this message on? iOS? Receiver?

I don’t think I have seen this exact message either. However, Dexcom specifically explains in the training that you always get at least an extra 15 days after the 90 days, so I am 99.99% certain that you will be able to restart properly – as long as you are positive that you are coming up on 89 days, not 15 days later.

@Robellengold - Go into the settings and see what is listed for the activation date of the transmitter.
The “22 day warning” should come on day #90.
Your Receiver or App will have an accurate recording of the date the transmitter was activated.

Also - If you received the message about “this is your last session…” then DO NOT stop the sensor early. You will not be able to restart it against that transmitter.

ah OK, my calcs are wrong - it got started on June 23rd - so that means today is day 105 and friday when the sensor ends is day 106 unless I’m wrong. But that would means from your advice above I can restart it on friday as its day 106 only not 107 - or I could do it today a day early as its day 105 and I should be able to restart for another 7 days ? I got the message on day 99 effectively

I used to do the calculation - you put in the start date and 105 and it comes up with Oct 6th tomorrow as day 106, so today Oct 5th is day 105. Do you think I can restart it as I have 8 days to day 112 even though I got that message ?

@Robellengold - I agree that if June 23rd is Day #1 then Day #106 would be Oct. 6th. (I use Excel)

I would have said that YES - it should be able to restart because today being Oct 5th (depending on your time zone - lol) should still have 8 days left. Possibly 7 if you factor in the time of day and when that fits. In any event it should work. But on the other hand, you DID get that message about it being the last sensor session so that indicates it would not work.

So, if you feel like testing it out then stop and start ASAP. See if it works. I give it a 50% / 50% shot. lol.

On the other hand if you want to play it safe and wait for your transmitter to arrive then do not stop your current sensor as it is a very real possibility that you will not be able to restart against that transmitter.

Although if the sensor is going to hit its 7 day mark on Friday anyway then I think you increase your chance of being able to get a restart if you go early and shave an extra day by doing a stop/start right now? Worst case scenario you lose one day of cgm data. Best case scenario you gain an extra 6 days? Without knowing for sure you will have to make your best guess.

EDIT: still thinking. I do think that if you already received the message about this being your last sensor session and if you then run that sensor the full seven days (which is probably what the message assumes you will do) then the most likely scenario is the transmitter will at that point not allow another session to start.

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In our last cycle, we failed to get the last sensor session to start. I did not pay perfect attention, but counted 104 good days before the restart, so I thought our failed restart was on day 105. It is possible, however, that I could have been off one day due to miscalculation, and that it could have been on day 106. It is even possible that it could have been day 107, as per @Thomas’s calculation :slight_smile:

So this leads me to believe that we should be able to complete 105 days, meaning that if you restart on day 105 you should be able to do it. That would mean that, according to this rule, if you started on June 123, you should be able to restart on October 5 – but possibly not on October 6. But this reasoning could be wrong by one day, meaning that possibly you would not be able to restart after October 4.

I don’t think that the Dexcom message on day 99 saying that it is the last session means that you could not restart it a couple of days early for instance. Imho, on the other hand it is fairly likely that the message is right and that restarting on day 106 will not work.

haven’t done it yet, but decided to check on my dexcom transmitter which I bought on monday and they said would get here today. No credit card charge which was strange, so i called them and they told me they hadn’t sent it because they hadn’t got doctor authorization. Basically the operator monday flat lied to me and said it was all done and in the post, he took my credit card details and did nothing about it. They haven’t even contacted my doctor for the authorization (which they said they had) - unbelievable. It will be a long argument now with them when they track him down as I want a free transmitter from them because of this and won’t shut up until I get one ! but means I am without for 1 wk and I start my new job monday so the worst possible time

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Your session ends tomorrow anyway - right?
Your best chance at a restart is to try now.

If it doesn’t work well - it was going to be done tomorrow anyway.

But a chance it might restart today. Every hour gets close to the point where it will refuse to restart however.

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Yep I did it, the tech guy said it wouldn’t work after the two hours it would stop so we will see, but I got the same message that this was my last session so I hope its OK - I had no choice anyway due to their incompetence- its amazing how utterly reliant you become on them - the tech guy told me to use test strips which horrified me now !

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I don’t think it would have gone into the two-hr warm up if it was not going to work.
Do you use both the Mobile App and the Receiver? Both should now have the two-hr pie chart running. (Although you of course only do the sensor start on the one and it replicates the status to the other device through the transmitter - might take up to 15 minutes but usually about 5 mins.)

Good Luck !!!

I think you might have been able to squeeze the last week out of the transmitter !!!


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I hope so, the two hour warm up is there - but I don’t have the receiver just my phone (iPhone) - at the same time the insurance company just called and said I was approved and they were sending me a transmitter - quite unbelievable timing

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Did you never have a receiver?

Also - are you getting the typical shipment of a pair of G5 transmitters with the single order?

Make sure to ask the insurance company what date you can place a reorder. They probably count one G5 as 90 days and might let you order around day 85. (or double if they ship a pair of G5 with the one order) So if you can actually stretch the transmitter to 112 days or so, it would let you (on the next order) actually get the transmitter a bit in advance so you don’t get stuck in as tight of a situation.

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