Pre-soak, hotswap, and 65 minute “warm up” for G6

Since we use Loop (ok…and because we just like having as much continous BG coverage as we can possibly get with the supplies we have)…we had gotten into the habit of “pre-soak and hotswap” with the G5 system.  If you haven’t heard of those terms before, let me explain them quickly.

Pre-soak:  Inserting a sensor hours in advance of before you intend on putting it into service.  Why pre-soak?  When you insert a sensor, there are micro-traumas under the skin that take some immune response.  Chemical changes and tiny micro-responses to the “insertion trauma”.   Plus there’s a coating on sensor wires that needs to come into equilibrium with the surrounding tissues where you have inserted.  That time to equilibriate with the new tissue surrounding is why there is a 2 hour warm-up.  It’s a balancing time for the system to settle down from the trauma of insertion.  You’ve probably already seen this yourselves if you’ve noticed that even the first 6-10 hours after warm-up can still be jumpy.  So, pre-soaking a sensor is a way to let the new sensor settle into its surroundings before putting it into use.  This helps the sensor start off right away with less jumpiness and more closely holding calibrations quickly.

In order to pre-soak, you need to NOT wait for your existing sensor to fail.  In other words, when you start to suspect that your sensor is going to fail soon, or you notice that it isn’t holding calibrations well, then you would want to go ahead and insert a new sensor ahead of time.  YES, this means that the person is wearing two sensors at once…(1) the existing one that is soon to fail and still has transmitter in it and (2) a new one, just inserted, that doesn’t have a transmitter in it yet.  For safety, you want to go ahead and put a band-aid, wrap, or dead transmitter to hold down the little flap in the middle of the new sensor that attaches to the wire in the skin.  You don’t want that flap accidentally being pulled up while the sensor is presoaking.

Hotswap:  Hotswap is when you take the transmitter directly from one sensor over to another without stopping the sensor session.  The idea being that you are trying to avoid the two-hour warmup.  While some people get lucky and have minimal downtime during a hotswap…I have ALWAYS had 65 minutes without CGM data right after a hotswap.  It’s not surprising to have some ??? from the hotswap as the transmitter is noticing that the environmental conditions from one reading (in old sensor) and next reading (in new sensor) are very different.  The ??? is giving the sensor time to “find its legs” again and get used to the new surroundings.  From what I’ve experienced, that’s a 65 minute wait for the ??? to clear and BG data to start coming in.  So, while the hotswap doesn’t totally avoid the whole 2-hour warm up, it can shorten it to about 65 minutes of time without BG data.

Here’s the important part though…you really should only do hotswaps with a presoaked sensor.  That 2-hour warm up gives a chance for the sensor to settle in…so hotswaps should only be done onto a sensor that has had at least 2 hours soaking, if not more.

For the G5, the hotswap wouldn’t stop your existing session…it would just keep going.

But, for the G6 as outlined below, it does involve stopping and starting a new sensor session.  So…technically not the same kind of “hotswap” that you did (or will do) with a G5…but same idea.  Avoiding the full 2-hour warmup by using a pre-soak with it.

Can the G6 do a pre-soak and hotswap?

Tonight I experimented with trying a pre-soak/hotswap with the G6 for the first time.  Our sensor was starting to show signs of wear.  Normally we test once each morning to make sure the sensor is still accurate.  This morning the sensor was off by about 15 mg/dl.  Sure, not a huge amount…but for the G6 this is usual for us.  And then we noticed a few steep BG changes that clearly were just out of place and unusual for the G6 trends we normally see.  If you look at the screenshot below, the red dots are what her finger check was on the meter.  You can tell that the first check of the morning was quite a bit higher than the sensor value, and then the second check of the morning (done to test the sensor since it was off in the first check) showed that it was off quite a bit but this time low.

Noticing that the sensor was on its end of days (this was day 11.5 for us…about average), we did the following steps to have just 65 minutes of lost BG data vs the usual 2-hours.  Extra bonus?  When a pre-soaked sensor comes online, it doesn’t have the jumpiness that a new sensor usually has.

Pre-soak, Hotswap Procedure
    1. Got out a new sensor.  Took note of the new sensor’s code.
  1. Got out the receiver and WHILE between BG readings (they happen every 5 minutes), did a “stop sensor”, “new sensor”, entered sensor code from above, and then “start sensor”.  Immediately after starting the new sensor, I put the receiver in a faraday bag (you can put it in microwave, etc) to let the two hour warm up go by without connecting to transmitter again.
  2. Inserted the new sensor from step 1 onto Anna’s other arm.  Wrapped the new sensor in vet wrap to keep the sensor protected while no transmitter was in it.
  3. Waited 4 hours.  Ideally, I like to pre-soak for about 6 hours with the G5 system, but 4 hours is the way our life worked out tonight.  It was my first try doing this with the G6, so I wasn’t sure what to expect.  (Spoiler alert: four hours seems to have worked nicely)
  4. After 4 hours, we took the old sensor off and removed the vet wrap from the new sensor.  Immediately moved the transmitter over to the new sensor and then took the receiver out of the faraday bag.  Pretty soon after (less than 5 minutes), the transmitter connected and we got the following on the screens (both I expected).  The transmitter noticed the dramatic difference between the old sensor’s surroundings and the new sensor’s surroundings…and thus begins the ??? time period. 
  5. The next thing that happened was we got one errantly high BG before the session when to ??? sensor error for 65 minutes.
  6. After 65 minutes, the G6 came back online with a value of 149, and finger check was 163.
  7. We calibrated and VOILA…our new pre-soaked sensor was online, super accurate and not jumpy at all with only 65 minutes of lost BG data.  Here’s to the next 10 days of awesome G6 use.

So why doesn’t everyone do this?  Because a lot of us like to squeeze every last day out of our sensors and we end up having them completely fail before we start a pre-soak.  BUT, I have found that I usually can see a G6 sensor failure coming up about 6 hours ahead.  We tend to see either a few missed BG readings start to happen, jumpiness in the data, or calibration drifting.  Given that heads up, this process will be pretty easy to implement for the G6 going forward.  Small amount of pre-planning and we can get immediately smooth CGM data on a new sensor session with just 65 minutes of downtime.  Pre-soak, receiver warming up in faraday bag, hotswap, wait 65 minutes and new session underway.

 

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 several ways to restart a G6 sensor, listed below from easiest to hardest. (Technically, Options 1 and 2 are so much easier than other options…that it’s almost not worth doing the others)

  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

UPDATE:  It used to be that I thought that you could not restart a sensor if it had expired, without using Option 3 or 4…turns out this is not true!  If you accidentally did not remember to start and finish Options 1 or 2 before your sensor session expired, don’t fret.  I have used Option 1 to restart an ended sensor (basically just start on Step 4 of Option 1, but you don’t need to wait for a new BG to come in…because the session has expired).  I haven’t personally tested how Option 2 would work in that situation, but it should work just the same.

However, do not end up in limbo…don’t start a restart process an hour before a session ends.  Either start/finish Option 1 or 2 far enough in advance that you can complete the restart entirely…or wait until the session has ended and then begin a restart.  The in-between process doesn’t work well, so pick a version and follow-through.

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.

We start and finish this whole process before the session is due to expire…so about 3 hours before the end of session, or sooner, we start the receiver going on the steps below.

  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” and “no data” message.  That’s a good thing.  Don’t worry about that. You want that.
    • 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 “no data” message will be replaced with a warmup message when the receiver will connect with the transmitter again.  The warmup circle looks like a 3/4 completed warmup circle, but don’t worry, it only has 5 minutes until you’re session is ready to start again.
  10. 5 minutes after the warmup circle appears, 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).
  11. 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.
  12. 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.

This process can be a little more prone to errors if using an android phone…some android phones reconnect with BT devices pretty aggressively I’ve heard.

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

SIDE NOTE:  I have heard from several t-slim users that this method does indeed work to restart the G6 for those users.

  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

This option resets the day-counter that the transmitter holds internally.  You know how the dexcom transmitter stops working at 112 days?  Well, this process resets that counter to zero and in the process will allow you to start a new session.  HOWEVER, it is a process to unpair-pair-unpair-pair the transmitter several times so, I’d recommend still using Option 1 or 2 above for regular sensor restarts.  Come back to these directions when you simply need to extend that 112 days.  Since it does work to allow a sensor restart…I’ll leave it here for the purposes of complete discussion of alternatives.

  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’ve heard from others that leaving it out for 15 minutes helps restarts…but I have not experienced the same.

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.

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.