But I wasn’t restarting….why the error??

Last night, we had a bleeder on a new Sensor #1.  A couple hours into its session, the sensor was losing data and just plain struggling.  Anna also said it was hurting a bit.  With those symptoms all together, we opted to pull Sensor #1 and put in a new one.

I called Dexcom to get it replaced while she put on her new Sensor #2 for the night.  Not long into warmup, about 35 minutes, the dreaded “Replace Sensor Now” message popped up accusing us (incorrectly) of trying to restart an old sensor.  (Turns out a lot of people have been having this happen to them, too.)

Anna thought it was weird, cleared the message without telling me, and tried restarting the warmup again.  Same message after another 35 minutes again.  At this point, she woke me up and told me she was having troubles.  The screen on the app was taunting us to start a new sensor, but that just didn’t sit right with me.  This was a NEW sensor.  It was about 3am now.  The last thing I wanted to do was:

  • Call Dexcom again,
  • Waste a brand new sensor,
  • Have to do a third sensor insertion, or
  • Dig out a transmitter from the brand new sensor.

So, instead I told her to just go to bed, and we left her app screen asking for a new sensor.  I grabbed the receiver out of the closet where we store it normally (we don’t usually use a receiver except for restarts).  I started a new session on the receiver, without even having the receiver connect to her transmitter first like I normally do when we are doing Option 1 restarts.  I just entered the sensor code for Sensor #2 that was still on her body, started a new session, put it in the faraday bag and went to sleep.  (If you don’t have a faraday bag, then you can keep the receiver out-of-range of the transmitter simply with adequate physical distance or by shielding it in a good microwave for the two hours.)  When I woke up about 4 hours later, I took the receiver out of the faraday bag.  It was showing “no data” and “signal loss” (like this old screenshot).  Exactly what I expected and wanted to see.  The receiver had stayed out-of-range of the transmitter for the whole warmup time.

 

Within 5 minutes, the receiver connected with the transmitter and was showing the last part of the warmup circle.  Also exactly what I expected and wanted to see.

And then 5 minutes after that…voila, receiver was showing its first BG value and my new Sensor #2 was no longer “needing to be replaced”.

So…the question is “Why would a brand new sensor be failing as if it is a reused one?”  I have heard from some people that Dexcom tech support is telling them that the sensor needs to pick up the “signs of trauma” that are expected from a recent insertion.  If the insertion doesn’t produce that kind of scatter and trauma in the data, the algorithm decides that this is a reused sensor.  It would appear the algorithm checks for this sensor scatter at 35 (or 65?) minutes (as that is when the “replace sensor now” messages pop-up).  By keeping the entire warmup period shielded from the transmitter, you bypass those scatter checks and can finish the startup.  I have no idea if all of this “trauma insertion check” is the truth…but that’s what Dexcom is telling people and it actually sounds plausible to me based on the observations.

The real problem is for consumers…we (and Dexcom, too) are having to be inconvienced as part of this “trauma detection” issue.  Pulling perfectly good sensors will cost Dexcom and/or the users money that doesn’t need to be spent.  And, even if the G6 doesn’t hurt for insertion (your experience may vary), nobody wants to have to do another pull of fresh adhesive off their skin unnecessarily.  Ouch.  Plus, Dexcom tech support is spending time answering phone calls about perfectly good sensors that are being rejected…adding wait times for us all unnecessarily.

So, until the “issue” is resolved (which I wouldn’t expect given the required FDA-approvals that went into this product’s design)…I highly recommend just pulling out your receiver and doing the restart like I’ve described above if you experience the same issue on a new sensor.  Save yourself the call to tech support, save yourself the new insertion, save the hassle.

Side Note:  This also confirms another nugget.  You could do this same procedure to restart an old sensor in the event you forgot to start the restart process in time.  Instead, wait for the session to end, then do this procedure that I’ve outlined above.  You’ll be able to restart an old sensor.

Side Note #2:  Based on what we know so far, I expect that a person who does not have a receiver could also just do Option #2 and restart similarly.     I haven’t tested it, but it would seem probable to be successful so long as there is no communication with the transmitter during the warmup.

No-Code vs Code sessions

On the Dexcom G6 system, the sensor is factory-calibrated according to a parameters and associated response in the sensor, and assigned a calibration code.  There is still work being done, but it appears that dexcom is using the following sensor codes:

  • 5915
  • 5917
  • 5931
  • 5937
  • 5951
  • 5955
  • 7171
  • 9117
  • 9159
  • 9311
  • 9371
  • 9515
  • 9551
  • 9577
  • 9713

Since these codes are presumably based on certain parameters and associated sensor responses, it would not be a good idea to just randomly choose a code for a sensor if you were uncertain of the sensor’s assigned code.  In other words, save the paper if you intend on restarting a session using a sensor code.

No-Code vs Code sessions

Sensor Code sessions: A sensor session that was begun using the assigned sensor code will not prompt for initial BG values at the end of the 2-hour warmup nor during the session.  For the 10 days, you should not expect to have any prompts for finger checks.  Having a sensor code entered should help the sensor maintain accuracy without the need for finger sticks and calibrations.

No Sensor Code sessions: A sensor session that was begun by choosing the “No code” option will ask for 2 initial calibration BGs after warmup.  After that, the session will prompt the user for a calibration point 12 hours later. If that calibration is not given, the prompt will reappear until it is given.   Inputting a calibration point resets that timer and you won’t be bothered for another 12-24 hours for a calibration.

Calibrations vs No Calibrations

Even with an active Sensor Code session (aka no-calibration prompts every 12 hours), there may be times when you should calibrate.  Dexcom has a very helpful set of G6 calibration guidelines to help you decide if/when to calibrate.  They are very useful for your 10-day old or less sensor:

  • When meter BG is less than or equal to 70 mg/dl, calibrate if sensor BG is 30 mg/dl or more different from meter value.
  • When meter BG is above 70 mg/dl, calibrate if sensor BG is not within 30% of the meter value.
  • If a calibration does not bring the sensor into acceptable limits, repeat the process 15 minutes after the first calibration.
  • If a series of 3 calibrations, each entered 15 minutes apart, does not bring the sensor back into acceptable limits, call Dexcom to discuss getting sensor replaced.

Using these guidelines, it was pretty easy to identify our recent bent wire sensor when it wouldn’t settle down early in our session.

Personal experience tells me those Dexcom rules are generally pretty good with a couple of additions:

  • Don’t enter a calibration point during times of rapidly changing BGs.  Try to find a smoother time of day where food and insulin bolusing is minimal and BGs are calm.
  • Don’t let the new sensor just flail on a bad starting point.  If the initial BGs starting a Sensor Code session are not within acceptable range of the meter readings, calibrate.
  • Don’t calibrate when very high or very low.
  • Don’t calibrate during compression lows.

If you get beyond 10-days and are having problems with the sensor maintaining accuracy, it’s best to just replace the sensor vs. suffering through jumpy, inaccurate BG data.

Q: Do I need to calibrate every time I am prompted in a No Sensor Code session?

A: Not necessarily.  You should calibrate at times that make sense as opposed to simply calibrating on a schedule.  For example, calibrating at 9:00 am just because a prompt showed up may not be the best idea if you just at a bowl of cereal at 8:30 am.

Q: What happens if I don’t calibrate when prompted?

A: If this is a normal, timed calibration prompt, nothing will happen.  Your sensor session will keep going.  You’ll get reminders until you finally do calibrate.  If you don’t want to be pestered with those alerts, you can go into your phone’s Notification settings for the Dexcom G6 app and turn off banner notifications.  Then you won’t be bothered by the little notification banners that appear.

Q: But what if I really never calibrate during a session?

A: The Dexcom G6 was approved for 10 days of no-calibration mode.  After that, you are in the “what makes you comfortable?” realm.  If you are restarting sensors, you will likely find that your sensor’s accuracy will decrease over time.  Calibrating may help restore accuracy for awhile.  However, you should never keep extending your sensor sessions to the point that the sensor is unable to maintain decent accuracy.  If you are needing to consistently calibrate often to maintain accuracy…it’s time to replace the sensor IMO.  Clinical trials were run with once-per-day calibrations.  There are lots of people who go days without calibrating.  Personally for us, we test (but don’t calibrate) every morning no matter what.  If we find the sensor is starting to lose accuracy on those morning readings, we plan on replacing the sensor.

Q: How has your sensor accuracy been after restart?

A: Pretty darn good.  We enter the sensor code during restarts and the sensor is maintaining its accuracy quite well.   We use CGM data in our closed-loop system, so accuracy is quite important to us.  We have not noticed any sudden or crazy drop-off in accuracy from a restart.

Q: How many restarts can you do on the G6?

We are finding, just like with our G5 experience, that we don’t get much extended time out of a restarted session before the sensor kind of “drifts” off its accuracy.  My daughter usually never gets more than about 13-14 days per sensor before we find the accuracy decreases enough that we want to replace it (remember we loop with this so accuracy is important).  I expect that your ability to maintain accurate sensor data with the G6 will be similar to whatever you got on the G5.   If you went 20 days before on the G5, you’ll probably get similar from the G6.

Restarted Sessions with Reset Transmitters

My original blog post on G6 restarts indicated that all restarted sessions would end up behaving as No Code sessions (i.e., sending calibration prompts twice per day) regardless of whether or not you entered a sensor code during the restart process.  After further testing and feedback from other users, I think I’ve narrowed down the source of the issue.  I was using a reset transmitter for much of my testing.  Subsequent testing has revealed a little more information:

Reset transmitters will cause EVERY session (new and restarted) to be a “No Code” behavior and you will get calibration requests…even if you entered a sensor code.

If you are using a normal transmitter that has not been reset, you should be able to restart sessions using the sensor code, and not have calibration prompts.   If however, you are using a reset transmitter, you’ll get calibration prompts on every session, even brand new sensors.  So if you intend on using your transmitter beyond 112 days or replace the battery, you can say good bye to no-calibration sessions.

How to enter code?

There have been reports of regular (non-reset) transmitters still yielding calibration requests even when the sensor code had been entered  I believe that issue, according to what I’ve been told and read, is an issue with the app’s failure to properly read the sensor code when users use the camera feature to enter the sensor code.  Therefore the current recommendation is to always manually type in your sensor code instead of using the phone’s camera.

 

I’ll be updating that blog post to reflect the new info shortly.

 

G6 transmitter battery replacement

The last big question on the G6 is “Can you replace the G6’s transmitter battery?”

Happy to report that you can, indeed!

I don’t have any fancy videos of it yet, because I was just focused on making sure I could do it vs. document it well on video.  I have replaced loads of G5 transmitter batteries using the guidance on this great video.  The same basics applied to the G6 transmitter work too…grinding down the grey plastic/epoxy, peel up the top tab carefully, and then pop the battery out.

However, I didn’t find the G6 quite as easy to replace the battery as with the G5.  It’s definitely doable, and I’d get better with practice.

Here’s the note-worthy differences and things I learned:

The G6 only has one battery, not two.  And the battery is accessed from the underside of the transmitter, as opposed to the top like the G4/G5 transmitters

The battery that the G6 uses is also quite a bit bigger than the G5.  If you want to order replacement batteries for the G6, here’s a link for a set on Amazon.  They are Maxell CR1632 3V lithium batteries.

The other major difference is that the battery (1) goes closer to the edge of the transmitter and (2) there are little wings to help the transmitter lock down inside the sensor.  Both of those combined to make it just a little bit more difficult to do the grinding down to expose the battery.

Here’s a picture mid-grind:

While you are grinding, you have to make sure not to go too low on the corners above the little locking wing indents.

You also have to be aware that the top tab on the battery has a different dimension than the G4/G5 transmitters.  The tab is much skinnier and has a few weak points built in…presumably to make the tab much harder to successfully bend up without breaking it.  There are three weak points that I could see.

Therefore, I was trying to be especially careful on that edge-located weak point as I ground down.  I did at first manage to get the 2/3 tab up just fine at first.  But, in removing the battery next, I ended up losing the long end of the tab (it broke at the middle weak point pretty easily).  The next time I do this, I will work harder to remove more epoxy around the edge weak point more carefully…will probably let me remove battery easier (see dicussion below) and maybe keep more of the tab.  It’s going to be a balance though, too much grinding and you’ll take the whole tab off at the edge weak point.  Based on the teardown pic though, probably salvagable if you did.

Battery removal was the hardest part.  I think it’s really important to get as much of a clean edge around the battery as possible.  Since the battery was much bigger than the G5 batteries, I found it was actually a lot harder to get leverage going to pop out the transmitter.  There was a lot more resistance to popping out than on the G5.  Possibly because I was too conservative on getting clean edge at first (definitely a contributor, I think)?  Or maybe because I wasn’t using a longer lever to start?  I don’t know…but eventually I did have to get out some vice grips and that made all the difference.  Since I was able to hold the transmitter more forcefully, I could apply a better pressure.  Worked SO well though, that it just popped super hard and fast.  Oops.  Did that little tab that normally sits under a battery go flying across my laundry room?  Could have.  I won’t know for sure until other people get a chance to open up their transmitters over the next few months.  😉

This is what it looked like when the battery was finally totally removed; a slightly shorter top tab (but still strong and in good shape) and a questionable bottom.

I assumed that there must have been a contact tab underneath that went flying.  So, I ground out a little on the bottom to expose the contacts and put a little bit of solder down.  Once I got that done, new battery was laid in and tab bent down to make contact on top again.  I did use a touch of super glue to hold the top tab down, just to be sure.

And voila…it works.  A G6 with a replaced battery.  I sealed it back up with two-part epoxy and the transmitter is working well again.

Don’t forget to use the reset transmitter app to be able to use the official Dexcom apps after a battery replacement.

 

Restarting G6 sensors and transmitter

“10-day hard stop on G6 sensors.” – love, Dexcom

Did that one thing alone stop you from considering the G6?  Well, good news…you can actually restart the sensors (and the transmitter).

There are four ways to restart a G6 sensor, listed below from easiest to hardest. (Technically, Options 1 and 2 (and to a lesser degree Option 3) are so much easier than Option 4…that it’s almost not worth mentioning Option 4)

  1. Use the G6 receiver to restart
  2. Use the phone to restart (without receiver)
  3. Use the resetTransmitter app
  4. Remove the transmitter from the sensor

Let me just get this out there early (and I’ll repeat it throughout)…the key to doing either Option 1 or Option 2…YOU WILL NEED TO FINISH THE RESTART PROCESS BEFORE YOUR 10 day SESSION EXPIRES.  Don’t wait for the “you have 2 hours left in this session” notification…by then you are already too late for Option 1 or 2.

Technically, you need to (1) start at least 2 hours and 10 minutes before the 10-day session expires AND (2) finish the restart process before the 10-day session expires…if you don’t you’ll be forced to use Option 3 (and that can take some time for the first time user).  SO…my piece of advice…set a timer, calendar appointment, or task at least 4 hours before the “Session Expires” time shown your G6 session’s settings.  That will buy you a little bit of nice breathing room on the timing of everything.  There’s no reason to wait until the last minute to do this process…day 7, day 8, day 9…they all would work.  If you like routine like my family does…EVERY WEEKEND we just do this process sometime during the weekend.  That way we aren’t hurried, I’m not watching the clock, and it becomes an easy routine, and we never bump-up against the 10-day deadline.  (We use Option 1.)

If for some reason you didn’t get a chance to prepare for Option 1 or 2 far enough in advance of the 10-day expiration, then you will need to use Option 3.  Said another way: Option 1 and Option 2 have a two hour and 10 minute process minimum to finish and if your sensor session expires before you finish, you will be forced to use Option 3 or 4 (or just put on a new G6 sensor).

The most common failure for people trying to restart is that they do not complete the restart before the session expires.  They either start the process too close to expiration, or get distracted and forget to come back and finish the process.  Planning ahead will help avoid this most common mistake.

So let’s discuss each of the processes in detail.

Option 1: Use G6 receiver

This is the easiest and preferred method because you don’t have to lose BG data during the restart process.  You can just keep looping (if you are a looper) and watching BG data on your phone, Nightscout, and Follow apps the whole time.

To use this process, you do NOT have to be using a receiver on a regular basis.  We only pull the receiver out in order to do the restarts.  Normally, it sits in the closet, turned off, between session restarts.  I think of the receiver as a magic restart wand that we pull out of the closet every so often.

Remember to start this process far enough in advance that you will finish it before the “Sensor Expires” time.

  1. In your Alerts settings for the receiver, it’s a good idea to turn off the “signal loss” alert during this process.  Your receiver is going to have signal loss for two hours and it would be annoying to hear that alert for the whole time.  Just a good idea before you get started.
  2. If you don’t normally use the receiver, go ahead and turn it on.  Get the receiver connected with the transmitter.  Shortly after (about 5 minutes) the receiver connects, the receiver will start reading BGs from the existing session already going on the phone.
  3. Watch the receiver get a fresh BG value.  Usually this happens just seconds after the phone app gets a new BG.  During this process, the transmitter and receiver briefly talk and then disconnect from each other for the next 5 minutes.  We are going to use that disconnected state to our advantage to restart the sensor.
  4. Wait about 15 seconds or so after the new BG value came in and then press the “Stop Sensor” option ON THE RECEIVER (not on the phone).  You’ll be told “Are you sure you want to stop your sensor?  It cannot be restarted, a new sensor is required.”  Answer Yes.  You’ll see a little progress bar go by for stopping sensor.
  5. On the screen that appears after the progress bar, press New Sensor.  You’ll be promoted to choose between “No Code” or “Enter Code”.  You can choose either.  If you choose to “Enter Code”, go find your code from when you originally inserted the sensor (the one printed on the adhesive cover of the sensor).  Contrary to early rumors, not all the sensors in a box have the same code. That code is the calibration code for the particular sensor wire that sensor is using.  If you don’t have that code saved, go ahead and choose “No Code” (don’t just randomly use the code from a different sensor in your supplies).
  6. After you finish with the Code entry decisions, you’ll need to press the “Start Sensor” button that will appear on the receiver.  You’ll see a “starting sensor” progress bar for a few seconds and then the 2-hour sensor warmup countdown circle will be displayed on the receiver.
  7. From this point forward for at least two hours…you need the receiver to NOT COME INTO COMMUNICATION WITH THE TRANSMITTER.  There are several ways to do this, some ideas:
    • Put the receiver in the microwave.  The microwave blocks the communications between the receiver and the transmitter very effectively, just make sure you don’t turn on the microwave during the 2+ hours you’re waiting, or
    • Put the receiver in a faraday bag (costs less than $10 and it can act just like the microwave, but a lot more portable and easy to manage), or
    • Put the receiver “far enough away” that it stays out of range of the transmitter.  Neighbor’s house, the corner of your backyard, etc.  Just so long as it is far enough away that the transmitter and receiver won’t accidentally talk to each other during the 2+ hours of waiting.  This is the second most common failure point for people trying to restart…they do not adequately keep the receiver from communicating with the transmitter during this 2 hour wait.  I highly recommend using a microwave or a faraday bag for this option to prevent accidental communication.
  8. During this 2+ hours of waiting, the receiver will have “signal loss” message.  That’s a good thing.  Don’t worry about that.
    • You can wait longer than 2+ hours without a problem…so long as you don’t wait past the “Sensor Expires” time on the phone.  
    • Also during this 2+ hours of waiting, you’ll have BGs on the phone app uninterrupted.  Your Nightscout site, dexcom follow app, dexcom G6 app, and Loop app (if you use it) will all continue to work as usual.
  9. After waiting 2+ hours at least (I usually go at least 2 hours and 10 minutes just in case), bring the receiver back into communications with the transmitter.  Within 5 minutes, the receiver will connect with the transmitter again.  And then 5 minutes after that, the receiver and phone will start showing BGs again for the newly restarted session (or the “enter 2 calibrations” request if you chose a “no code” session or used a reset transmitter).
  10. If required, enter the calibrations in both the phone and receiver at the same time.  If your session did not require immediate calibrations to start the session, it is still not a bad idea to check and make sure you’ve restarted BGs at a reasonable value.
  11. Congrats, you’ve just restarted your G6 sensor session.  Your newly started session will expire 10 days from the time that you did Step 5, so plan ahead if you are going to do any subsequent restarts.

Here’s the video for the G6 Option 1

Option 2: No-receiver restart

For non-US residents, sometimes you can purchase the G6 system without the receiver.  So while you can still restart the sensor session without it, the disadvantage (vs. using Option 1) is that you will not see BGs for two hours during the restart process.

Remember to start this process far enough in advance that you will finish it before the “Sensor Expires” time.

  1. In phone’s bluetooth list (in iPhone Settings), “forget” the Dexcom transmitter ID.  In fact, “forget” all your old Dexcom transmitters if you don’t regularly delete them.  Old ones don’t need to be saved.  By forgetting the Dexcom transmitter, we are preventing the transmitter and app communications during the restart process…and that’s a good thing.  We don’t want them paired during the 2 hours.
  2. Go to G6 app on the phone and “stop sensor” from the Settings menu. You’ll be told “Are you sure you want to stop your sensor?  It cannot be restarted, a new sensor is required.”  Answer Yes.
  3. On the screen that appears after, press “New Sensor”.  You’ll be promoted to choose between “No Code” or “Enter Code”.  You can choose either.  If you choose to “Enter Code”, go find your code from when you originally inserted the sensor (the one printed on the adhesive cover of the sensor).  That code is the calibration code for the particular sensor wire that sensor is using.  If you don’t have that code saved, go ahead and choose “No Code” (don’t just randomly use the code from a different sensor in your supplies).
  4. After you finish with the Code entry decisions, you’ll need to press the “Start Sensor” button that will waiting on the app’s main screen.  You’ll see a “starting sensor” progress bar for a few seconds and then the 2-hour sensor warmup countdown circle will be displayed on the phone.
  5. Wait at least 2 hours, but not so long that the old sensor session will expire during your wait.  If the old session expires before you finish the remaining steps…you’ll have to move onto Option 3 or 4 (or replace the sensor).
  6. Your G6 app will also display “signal loss” during this time.  That’s good, too.  You want the transmitter to stay unpaired and “lost” during the warmup wait.
  7. After the 2 hour wait, restart the phone (hold down the power button and slide to turn off the phone).  Open G6 app. This will trigger the phone to try to re-pair with transmitter.  Accept the pairing request now that you’ve waited at least 2 hours.  If you don’t get a pairing request within 5 minutes of the restart, you may need to restart the phone one more time.
  8. About 5 minutes after accepting the pairing request, you’ll be greeted with BGs again for the newly restarted session (or the “enter 2 calibrations” request if you chose a “no code” session or use a reset transmitter).  If prompted, enter the calibrations and you’re good to go.

Option 3: Reset Transmitter

The last resort for restarting a G6 sensor session, Option 3 should be saved for when you’ve accidentally lost track of time and won’t be able to finish Option 1/2 before the 10-day clock runs out.  Note: There is a pretty significant side effect of resetting the transmitter. 

Reset transmitters will cause EVERY session (new and restarted) to be a “No Code” behavior and you will get calibration requests…even if you entered a sensor code. So before you reset a transmitter, ask if you are prepared to have calibration prompts for all your remaining sessions using that transmitter.

  1. Build the ResetTransmitter app as described in my blog post here.
  2. Make sure your G6 session has ended.  You cannot be in an active session for a transmitter reset.
  3. Go to your iPhone’s Bluetooth area (in Settings) and “forget” the Dexcom transmitter.
  4. Delete the Dexcom G6 app.
  5. Shutdown and restart your iPhone.
  6. Open the ResetTransmitter app and enter your dexcom transmitter ID and press the Reset button.  Within 5 minutes you should get a pairing request to accept.  The reset success message will appear within a very short time after the pairing is accepted.
  7. IF you don’t get a pairing request within 5 minutes in Step 6, restart the phone again.  Double check all the dexcom transmitters have been deleted from the bluetooth list on the phone.  Open the ResetTransmitter app again and see if you get a pairing request within 5 minutes.  (The toughest part of this process is getting the transmitter to successfully unpair and re-pair between apps.  Sometimes it takes a few restarts and patience…but it does work eventually.)
  8. After the transmitter has been reset, you can reverse the process.  Forget the Dexcom transmitter again from Bluetooth list, restart the phone.  Reinstall the G6 app and go through the setup screens as if you were starting a new sensor.  It won’t matter if you use a code or no-code session, as you will definitely be prompted for calibrations for any session after resetting the transmitter.  Once you get a successful pairing established, you can press the start session on your app.

Option 4: Remove the transmitter

The G6 transmitter is surrounded by plastic entirely.  The locking wings for the transmitter are located under and inside the plastic ring surrounding the transmitter, making them very inaccessible by fingers.  Therefore, popping out the G6 transmitter is a bit cumbersome, requires some small pointy tool, and frankly would be a little hard to do if your sensor is in an awkward spot to reach.  I managed to do it with a simple tool by myself with the sensor on my arm (see video below), so it’s not impossible.

Technically, if you remove the transmitter, you can replace it back onto the same sensor (and tape it back down so it stays locked in place, if you’ve busted the hinge point in the process of removing the transmitter).  This would allow you to restart a sensor session on the same sensor.

I’m only mentioning this option for full disclosure of ALL the options…but really this shouldn’t be used.  It’s so much easier to use one of the first two options.  Although, it may be preferable to Option 3 given what we know about the side effects of resetting a transmitter for calibrations now.

Video of how to remove the transmitter:

Restarting G6 Transmitter (avoid the 90-112 days Dexcom shut down)

The Dexcom G6 transmitter is just like the G5 transmitter in that Dexcom artificially kills the transmitter by 112 days of use after first activation.  If you’d like to use the transmitter beyond the 112 days, and instead use the transmitter until the end of its battery life, you can use the same process described in my G5-reset-transmitter post.  The G6 transmitter can be reset at any time just like the G5 transmitters.

Reset G5 Transmitter

First, let me preface by saying that I adore, love, respect, and covet my Dexcom system.  It gives us a stability with type 1 diabetes that we would never be able to do without now.  But what I’m about to tell you is a bit of a hack on their system.

There’s been one thing I really have not enjoyed about moving from the G4 to the G5 system about four months ago.  The G4 transmitters were warrantied for 6 months, but usually the battery in those would go for a year…meaning we had the opportunity for much of the transmitter’s useful life to have a backup on the shelf at all times.  If the G4 transmitter failed for any reason, we could pick one off our shelf and not stress about how long it would take to get a new one.  Overseas travel and 2-week long diabetic summer camps were not a big deal…we could pack a backup.

Then we switched to the G5 system at the beginning of this year so that Anna didn’t have to carry a receiver while she did track team workouts.  This dramatically improved the likelihood that she would stay in good BG range during workout because our DIY loop system would have BGs available the entire workout to help her insulin needs.  If Anna had to carry a receiver during track workouts, that would’ve been the straw that broke the camel’s back in terms of diabetes gear she was willing to manage.

So, we’ve loved the G5.  It has worked well; not really having any problems with signal loss, BGs are accurate, we have enjoyed Clarity reports.  All good EXCEPT those G5 transmitters being shut-off by Dexcom  at 112 days.  At 90 days, you get a warning and your warranty is up.  At 112 days, your transmitter is artificially shut-off even though the batteries have some useful life left.  How much life?  Well, that depends, but for most users it is about a couple more months of life.

The problem with this system is that my insurance covers 2 transmitters in one order every 6 months.  So, for the first 90 days (3 months) after a transmitter order, I will nicely have a backup sitting on the shelf in case things go wrong.  BUT, for the next 3 months, I will have no backups on the shelf.  If that second transmitter dies early, I would have to wait for Dexcom to send us a new one.  If we were overseas or traveling, this could be very inconvenient.  I definitely won’t have one to send with Anna to her 2 weeks of summer camp based on how I can forecast our insurance refills already.

And here’s the really great news.  You can now reset the clock on that 112 day shut-off by building your own iPhone app.  This doesn’t buy you heaps of extra time…as the battery will only go for about 2 more months (maybe even less?) past 112 days…but that could be just enough time to start to be able to keep a backup transmitter on the shelf for longer between orders.

Another really good plus?  You can use this reset on G5 transmitters that have had their batteries replaced AND still use the Dexcom official app…you won’t have to try to use a different app (like Spike-App or X-drip+).

HOW TO BUILD RESET APP

What you will need:

  • iPhone (iOS 11.0 minimum)
  • (this may also work on iPod…but I haven’t tested it yet)
  • Apple computer (macOS 10.13.2 High Sierra minimum)
  • Xcode 9.3 (newer versions will work too…blogs are bad for “current” version references lol)
  • Apple ID email

Check to see if you need to update your macOS based on the version of iOS you have.  You can check your macOS by clicking the apple logo in your computer display’s upper left corner and selecting About this Mac.   If you are due for an update, click the Software Update button.

Download and install the app called Xcode from the App Store on your computer.  When the installation is finished, open Xcode by double-clicking on it from your Applications list.

Note: If this is the first time you are opening Xcode, you may get an initial message telling you that Xcode is installing command line tools.  Please let that run and complete the installation.  Command Line tools are a needed installation.

Go to the Xcode menu on the top of your screen, and click on Xcode and then Preferences...

Within Preferences, click on the Accounts tab and then the + button in the bottom left corner to add an account.  You are going to add an Apple ID type account.

Enter in your Apple ID email and password.  This process automatically makes a free Apple Developer account associated with your Apple ID email.  The account will show up in your Xcode preferences now with your name and (personal team) as a suffix in the name.  Once your account is added, close the Preferences screen by clicking on the red circle in the upper left corner.

Download the code for the ResetTransmitter app that we are going to build by clicking HERE

Open your downloads folder and navigate to the CGMBLEKit-master folder and then find the file CGMBLEKit.xcodeproj folder.  Double-click on that file and the project will open in Xcode automatically.

Click on the open button when the message appears asking:

“CGMBLEKit” is a project downloaded from the Internet. Are you sure you want to open it?

{Take the time now while the project opens to plug in your iPhone to the computer using your lightning cable.  Please accept any prompts about trusting your computer and unlock your phone so that it stays awake through the build process of the app that we are about to finish.}

Now click on the CGMBLEKit at the top of the left column, and then click on the small box as shown on the screenshot below to show the list of “Targets” below it.  Select the “ResetTransmitter” target.

Now, look at the screenshot above.  See that part highlighted in blue? You will need to change the loopkit part of the Bundle Identifier to a unique-to-you word.  Make sure that when you make the edit, you do not delete the period before and after.

Once you have the name edited, then go down to the Team section and select your (personal team) signing name from the drop down menu selection.  [Note: if you have a paid developer account, you can use that signing name instead.]

After you finish signing, a Provisional Profile will automatically be created and you’re close to done.

If you see a prompt under the status area below the Team about your device not being registered, please click on the Register Device button provided there to register the iPhone to your developer account (see screenshot below).

Now, navigate up to the top of your window and select two things; one from the left side of the box you’re going to select ResetTransmitter and from the pop-out, you’re going to select your phone’s name from the very top of the device list (not just your phone model…you want to go all the way to the top of the list for your phone’s name).


Stop and double check….most common mistake is forgetting to select ResetTransmitter as shown in the screenshot below and mentioned above.  Do not leave the selection on CGMBLEKit…if you do, your app will build properly nor will it appear on your phone.


If your phone/device name has (untrusted) after the name (see screenshot below), please open the phone and click on the Trust button that should appear on the main screen.  If the (untrusted) tag hasn’t disappeared after that, just unplug and replug the phone into the computer.  That should get rid of the (untrusted) tag.  If you try to build an app onto an “untrusted” device, you’ll get an error message reminding you to do the steps above.

When you’re done, the screen should look like the screenshot below; ResetTransmitter on the left, your phone’s name on the right, and no red error messages under the signing team area.  If your screen looks correct, then go ahead and press the build/play button.

Depending on if this is the first time you’ve built on Xcode, you may get prompts for codesign access and keychain access.  If those prompts appear, please enter your computer’s password and click on the always allow button to confirm.

Also, if this is your first time building with this developer account onto your iPhone, you may get another warning that the app could not launch because an issue with trust on your Developer Account on your phone.

Follow the directions on the warning.  Open your iPhone Settings >> General >> Device Management and then select your Developer App certificate and trust it.

Once you click the Trust on your iPhone, go back to Xcode, click on the blue OK button for the warning and then press the build/play button one more time.  This will finish the build of the app onto your phone.  Success!  You can unplug your phone from the computer and use the app now.

 

USING THE RESET APP

There is some warning messages in there about the use of this app.  When the app was first written, the code writers were uncertain how Dexcom Share and Clarity servers would treat information coming from a clock-reset transmitter (i.e., would data still be uploaded properly). The app has been in-use by many people now and the Share and Clarity services are, thankfully, not impacted by the reset transmitters.

You cannot reset a transmitter that is currently in a session and/or paired with Dexcom or Spike, or any other device/app.  So, stop any currently running sessions, and quit the dexcom app.   Forget the transmitter from your iPhone’s bluetooth list.  Forget all Dexcom transmitters from the list…no reason to keep old ones that you aren’t using anymore anyways. Re-open the ResetTransmitter app, enter your Transmitter ID and press the red Reset button.  Within 5 minutes you should get a pairing request.

If you do not get a pairing request and instead see a message “Unable to parse auth challenge: timeout” that means your transmitter is still busy with another app.  Double-click the iPhone’s home button and scroll through the open apps.  Upswipe on the Dexcom and the Reset apps to close them.  Restart the phone, re-open the Reset app, enter in the transmitter ID again and press the red Reset button again.  Within 5 min you should now see a pairing request.

If you STILL don’t see a pairing request, some users have reported that turning off Dexcom’s cell data within the iPhone Settings >> Dexcom G5 app can also help release the transmitter from Dexcom app’s influence.  If that fails…you can try deleting the Dexcom app and reinstalling it at the end of the reset process.

If you still don’t get a pairing request, make sure the transmitter is within pairing range of the iPhone (but not in active session).  The Reset app needs the transmitter close enough to be able to pair with it in order to reset the clock.

Once you press the pairing request, the reset command is immediately issued and you should get a confirmation screen like below:

You can now close the Reset app (double-click phone’s home button and upswipe Reset app) and forget the transmitter in the iPhone’s bt list again.  Reopen your Dexcom app and you’ll be able to use your transmitter for another 112 days or until the battery gives out…whichever comes first.

The free developer account that you signed the Reset app with only allows the app to be used for 7 days.  After 7 days, the app will simply produce a quick white screen and self-close if you try to open it.  You can rebuild the app anytime after the 7 days to use it again.  Simply double-click on the file in your CGMBLEKit folder download to open the project in Xcode again, plug in your iPhone, and press the build/play button.  All your previous changes will have been saved, so the rebuild is quite easy.

You can reset any amount of transmitters.  The app does not know transmitter ownership, nor does it have a limit on how many times you can use the app to reset transmitters.

The transmitter does not have to be on a sensor in order to be reset, just needs to have battery life left and not be paired already with another app.