Medtronic 670 vs Tandem Tslim


As FYI so it is not a surprise. When we switched from the Animas to the Tandem, the cartridge change (which we do every three days - both cartridge and infusion set) is not as simple and quick as it was with the Animas.

Initially it was a bit aggravating on the Tandem because we were used to the Animas approach for the cartridge change.

If you read various threads on these forums related to Tandem cartridge change, you can see there is the official Tandem way to do the cartridge change and then different people (such myself) have made slight “tweaks” to the process which they may feel is preferred either for better results or faster change. In any event, just be prepared for a learning curve here which otherwise might have been unexpected.

In my opinion and now that we have been on the Tandem (and off the Animas) for some time now, it is just one more thing that you get used to and not something that I personally would use as a deciding factor in which pump to go with.


In my case, I’ve always used a Medtronic pump but had to switch from Dexcom to Guardian 3 in order to use auto-mode on the 670G. I wore both sensors for the first week or so (my Dexcom was still good, so I didn’t pull it). The Guardian was at least as accurate as the Dex, compared to finger-sticks. It has also had far fewer Bluetooth dropouts, possibly b/c it uses a rechargeable transmitter battery so it doesn’t have to be as power-stingy as the disposable Dexcom transmitter. And even if you don’t run auto mode, having the sensor “talk” to the pump allows it to do Suspend Before Low, which for a lot of people is a very reassuring safety feature.


  • Changing sensors is a more lengthy and laborious process because of the wait for the battery to recharge and all the crazy taping you’re supposed to do.
  • You can roll over to a second session, as with the Dexcom, but it’s a bit more difficult (you have to physically disconnect the sensor from the transmitter for a few seconds, which is trickier than it sounds)
  • As yet, there is no smartphone app. It’s nice to have the data on the pump, but there are lots of times when having it echoed on your phone is more convenient. Not to mention apps like Glucogram that let you have it at the top bar of your desktop computer.


I know that the Guardian is an improvement over the Enlite. If I did go with the 670g, I would have used manual mode with the Dexcom until I felt more comfortable with the Guardian. I did use a loaned Medtronic pump for awhile last summer. My deciding factor, in part, is because with the Tandem Tslim, I won’t have to deal with the Dexcom touch screen.

Also, am wondering if, eventually, Tandem users will have to go Medtronic. I asked an investment friend to check on TNDM on NASDAQ. He didn’t recommend the stock. Then I looked up Tandem’s stock price and p/e earnings stuff. I don’t really understand that stuff, but it didn’t look good for TNDM. Hope I am wrong.


In terms of financials, bear in mind that Medtronic is a corporate giant where the pump division is only one small piece of the larger whole.
As recently evidence by Johnson & Johnson which is a huge corporation with a Market Cap about 3~4 times larger than Medtronic, the size of a company does not necessarily indicate their future intentions.

Tandem is a much smaller company as well as being a “Growth” company. The Tandem t:xlim X2 is their second model pump. Certainly they are struggling. P/E is not relevant for Tandem at this point. Their stock price certainly shows the struggles they face.

We were aware of the company situation when we switched to the Tandem from the Animas and certainly hope they are able to continue. Tandem continues to release periodic news such that we know they are continuing to work and have not lied down to allow any other company to steamroll over them.

It is my opinion that if Tandem is able to release the PLGS update per their goal of this summer, this could be a game changer for the company.

While we hope for the best, we are using our preferred pump technology (Tandem t:xlim X2) and supporting the company with our pump and supply purchases.

If thing ultimately do not work out then we will evaluate our choices at that time. Until then, we continue to hope for the best.


Sigh. That was a big factor for me. Not Tandem specifically, but I was looking pretty hard at Animas, then decided against it when I encountered the going-out-of-business rumors. Which turned out to be true, thankfully after I’d decided not to chance it. I’ve already been orphaned by one pump company (Asante Snap) and it’s no fun. No warning either, just an email announcing “Guess what? We’ve cratered!”

One other plus in the Dexcom column that I forgot to mention, or more of a minus in the Guardian one, is that the Carelink analytics kinda suck. I mean, the data visualizations etc are ok, but the thing is built in Java with all the security and browser/OS incompatibilities that go with it.


I am an Animas pump & Dexcom user in the same situation.
I just raised the 60 day offer with Tandem sales rep and was also told that offer is only for users with pumps under warranty.
I pointed out the language from the offer and will report how Tandem responds.
I suspect it is a case of sloppy wording. The offer says “customers with pump warranties that expire on or before…” what Tandem meant was "customers with existing pump warranties that expire on or before…


So, have been on Tslim for 10 days. I hadn’t realized how much would miss my Animas (yes, I realize there is always an adjustment period to something new). Yesterday has me confused. I woke up from a snooze, looked at my Tslim, which said 55. As I didn’t feel funny, and I wanted to know what a low alarm would sound like, I decided to wait to hear it. As the Dexcom frequently reads a false low and if I am dropping fast…I know it, I figured it okay to wait to hear the alarm. Never did hear it, it just dropped lower and then I felt ‘it’. Got up, ate glucose tabs, fingerstick showed 61. On the Tslim screen, it dropped to 47 but never heard an alarm. Called tech support.

Still don’t know what a low alarm would sound like. The tech guy had me hook up my pump to t:connect so that he could check on things. He hadn’t figured it out, said he would be looking at it more, that Saturday was his Friday and would call me Tuesday. I don’t get it. Something is wrong…either with me, the pump or with my ability to communicate with the tech. Whenever anything seemed off with the Animas, I was told to use backup plan and that a replacement was being ‘overnighted’ to me.

I guess I am still withing range of return. But I do like having to carry around only on device.


It is your choice to run the Tandem and Dexcom in integrated mode or not.
Reply back if this is of interest or you have questions regarding such.


So, as the CDE couldn’t get the Dexcom to work with the Tslim, was several days before that was figured out, I could now disconnect the Dexcom from the Tslim. That makes sense. Perhaps I will do that for awhile until basal and correction factor are recalculated. The CDE changed my basal. I need to make a trip to visit a cousin in a bad ALS situation but have been waiting until I am totally comfortable with Tslim. Or maybe go back to Animas for a week or so. It’s only malfunction was an occasional ‘no delivery’, easily fixed.

I would just need to get receiver out of ‘shutdown’, shut it down on Tslim, re-enter transmitter number into receiver, and start sensor. This is assuming I correctly figure out how to restart transmitter and shut down Tslim connection. Thanks, will think on it.


The steps I am familiar with to switch data reception of the Dexcom G5 transmitter from the Tandem t:slim X2 to the Dexcom receiver are a bit different.


I was just guessing, don’t actually know. How would you do it?


It is easier if you are fine with starting a new session on the G5 Transmitter. It can also be done without interrupting the current Dex session but that is slightly more involved. So here are the easy steps which involve stopping the session. Also - I am going by memory and not looking at the devices so just the gist without exact menu names.

  • Stop sensor session from the Tandem t:slim X2 pump
  • Put bogus Dex transmitter ID into Tandem. I like the generic 400000 as it makes it obvious this is not a real transmitter.
  • Turn on Dexcom Receiver
  • Change transmitter ID in receiver to bogus ID. (and go back to home screen on receiver)
  • Change transmitter ID in receiver to proper Transmitter ID you are really using.
  • (Above two steps force pairing to take place. Various shortcuts possible but this is generally a sure thing by the bouncing of the ID)
  • Start sensor on the Receiver

That should be it. Typical 2-hour sensor warmup from the Receiver.

As mentioned, it can also be done without stopping the sensor session so as to not require the 2-hour warmup but that is slightly different actions required.

The Tandem t:slim X2 will switch the user interface back from cgm integrated mode to what the X2 looked like prior to the cgm update once 24 hours have passed since receiving the last cgm data point. This is an automatic change and no user action will speed up nor slow down this UI reversion.


Okay, did first two steps. Plugged Dexcom receiver to charge, green marks came across but can do nothing else with it. It is now unplugged, goes blank after a bit, and green marks come back when I try to turn it on. Still can do nothing with it. When I was with the CDE, instead of stopping sensor, she did shutdown. I objected but she said I could start it again. Am wondering. Any suggestion?

Right now, I am just keeping it plugged in. Also changing sensor.


Describe what happens exactly after “green marks come across but can do nothing else with it”. When you say, “… goes blank after a bit …” what is it displaying BEFORE it goes blank? Would you be able to take a video of it and upload the video?

Is it possible your CDE did a stop sensor and then immediately did a receiver shutdown?
(Potentially bad). It would have been obvious if you then had to do a two hour sensor warmup from the Tandem after the Dexcom Receiver had been shutdown.

Also do you know when you purchased/received the Dexcom Receiver? The warranty on the receiver is 12 months.

Also note: Better not to change the sensor. Get everything working first. Just leave the same sensor in. Otherwise you could run through the sensors like water. This is about the Receiver - same or different sensor is not relevant. Just leave the old sensor in place for now until you get the Receiver situation worked out.


Yep, she stopped sensor and did shutdown. Had to wait two hours. It was a new sensor.

The Dexcom receiver has DEXCOM in green on top, and then down below those green marks that come on when receiver is ‘renewing’ (?) itself. Every once in awhile, it buzzes, goes blank, the in just a bit comes on with green DEXCOM and green marks going from left to right. It is probably a year or so old as they sent me the new touch screen version.

I haven’t changed the sensor. Will give Dexcom support a call, they will probably tell me to get out the touch screen new one, which I am now recharging. {I wish I were a drinking woman!}.



What exactly happens after the green marks go across from left to right?
Also do the “green marks going from left to right” process repeat by itself with no interaction from you or is that only when you (again) try to power up the receiver?

Note - This is sounding more and more like a failed Dexcom Receiver. But this is the old receiver - correct? And you mention you also have a new touchscreen receiver.

The old receiver was prone to an issue which (appears) to be as you describe and is put into that situation exactly by doing a STOP SENSOR followed immediate by a RECEIVER SHUTDOWN. Obviously a bug / defect. The solution to avoid that is to wait a minimum of 15 minutes (I prefer to wait an hour and take no chance) after doing a STOP SENSOR and before doing the RECEIVER SHUTDOWN.

Note that the new Dexcom Touchscreen Receiver is NOT afflicted with this bug.

To verify this with the old receiver, you can call Dexcom Technical Support and they can walk you through various troubleshooting procedures. For this it may require a longer than typical phone call with them but likely worth it before you were to actually throw the Receiver into the trash. I would want to be 100% positive the Receiver can not be salvaged and personally I would not feel I could reach that level of comfort without spending the time on the phone with Dexcom Technical Support. And who knows. Maybe you get lucky on the phone with them and they figure out a way to save your receiver.


Just got off phone with Dexcom. She told me to plug into wall instead of computer, had me push paperclip into whole. Nothing happened, so she told me to let it die and then try again to bootup, maybe more paperclip stuff. She is also checking some stuff (like my phone call them to yesterday). Confusion, soon will reattach Animas. I think I need to start again from beginning of training with a different person.


Yeah - I went through all this with Dexcom Technical Support also. Not to say it is not worth your time to do it as well. Dexcom Technical Support is really good in my opinion. If there is a chance to save the Receiver, they will explore the options. By the time you finish with them and if unsuccessful, at least you should have no thoughts left that some action was left unexplored.

In terms of the Tandem t:slim X2. You can absolutely run that without having the Dexcom integrated. It is completely supported and very feasible to run the Dexcom G5 Transmitter going to the new Dexcom Touchscreen Receiver.

With the Transmitter ID in the Tandem changed over to 400000 (you said you did that step) then there will be zero conflict between the Tandem t:slim X2 and the Dexcom touchscreen Receiver.

Actually this might be a good way to allow you to focus on learning the X2 without having the cgm stuff get in the way. Deal with all the cgm over on the Dexcom and then you can focus on the t:slim on the pump.

Give the Dexcom/Tandem integration another try after you have more experience with the Tandem.

IMHO there is currently not a huge benefit for the Dexcom/Tandem integration anyway. Minor convenience currently in terms of one device rather than two devices. The larger functional benefit is due to come this Summer when Tandem releases the Basal-IQ (formerly PLGS) update for the pump which will have the basal cutoff when a low BG is predicted.


Yes, simpler is better so I will just keep Dexcom separate for the time, get things adjusted. Actually, the receiver is easier to read. Also, I need to get my Animas basal rates into this Tslim. Over time I had it finely tuned. She changed it.
The Dexcom tech called back, says she will call again tomorrow morning. I think she is checking to see if she can get me another old fashioned receiver. The touch tone is charged, waiting for date, etc. Originally was going with MedT on auto with Dexcom so as to avoid touch screen (cold finger syndrome). When new touchscreen Dexcom came out, decided to go Tslim to avoid big Dexcom receiver. Now, I have two touchscreens.

I also have boxes of labelled 32" that are actually 23". They are still trying to figure what to do about that. I am so tired of pump stuff, for years Animas was great. Oh well, change happens. Thank you for your help!



One item that is obviously highly individualized and may or may not be relevant for you. When we switched from the Animas Ping to the Tandem t:slim X2, it took us quite a bit of time but we eventually came to realize that the Tandem “Insulin Duration” needed to be bumped up (for us) to 4-1/2 hrs.
We had been using 3 hrs for the “Duration of Insulin Action” on the Animas.

(Same concept - slightly different terminology between the two pumps.)

This certainly is a custom setting to be changed as appropriate for the individual. I only mention it as we had skipped over really thinking about this setting when changing pumps and it turned out to have a pretty big impact.