T:slim G4 - did anyone upgrade to the X2?

I have been on the t:slim G4 for a year and a half (after 16 years on Medtronic). I filled out the interest form to upgrade but as the deadline approaches I’m having cold feet. It sounds like I would lose the integrated Dexcom, at least temporarily. I’m not sure it’s worth it, versus waiting until my 4 years runs out and I switch then.

Has anyone made this switch or plan to?

We are on the Tandem t:slim X2 and using the Dexcom G5 although not integrated. As you say, we are waiting on the integration. Certainly hoping the first integration is available at some point this summer.

However we did not use the t:slim G4 so can not compare the two Tandem pumps. But without comparing, we are happy with the X2 and have no complaints at this point.

How does cost factor into it for you and when would your 4 years be up?

Thanks! There would be a fee for me to upgrade, which is not cost prohibitive. If I wait out the remaining 2.5 years and my insurance doesn’t change, there should be no out of pocket cost.

Since I have the integrated G4, I don’t have a CGM receiver other than my t:slim pump, so I imagine I would lose the Dexcom with the X2 upgrade.

@Pipli is there a date at which the upgrade price changes? Or would the upgrade price stay the same (as far as you know) until you hit the 2-1/2 years and then the insurance covers it fully?

Note that the Tandem X2 will NOT be compatible with the Dexcom G4 (transmitter) so you might also want to factor in what you have on hand in terms of the Dexcom G4 transmitters. The G4 sensors DO work with the G5 transmitter so that might be helpful.

If you have a smartphone, you can use that as the receiver for the G5. The Dexcom G5 supports both Apple and a selection of Android smartphones. (Actual list of supported devices is on the Dexcom website.)

I don’t have the G4 tslim, but I did just upgrade to the X2. I’ve been very happy with it and have had no problems. I don’t use CGM, but if I did and having an integrated pump was a concern for me, I think I’d probably just wait till my warranty was up. It was either use my warranty to replace my old tslim, the battery cover was broken off, and the black covering of the pump was starting to chip away in some places, OR upgrade. I figured I’d just upgrade.

I have the X2 and the G4. It doesn’t bother me that they are not integrated, maybe because I have an apple watch and use the Share2 iphone app to send my dexcom screen to my watch. I still need the dexcom receiver in the loop so there is some more stuff to carry but it works pretty reliably and its convenient to have my reading on my wrist.

Did you have the receiver already before you got the X2? I have the G4 but no receiver because it’s integrated with the t:slim. I didn’t realize that there were ways to have the G4 data sent to a cell phone from the receiver - I thought that was only the G5 that had that type of capability.

I’m still debating whether to upgrade. I have a question in to Tandem about the option to upgrade to a refurbished X2. The rep I spoke with said it was the first time she had gotten that question (specifically, if the deadline to upgrade is end of September but the FDA approval hasn’t come in yet to make the refurbished option a possibility by then, how would that work?). She hasn’t gotten back to me yet. If the less expensive option (refurbished pump) is not actually an option, I’ll probably just wait out my warranty and upgrade then. What I have currently, the t:slim G4, is working well for me, so I have no real need to change to something different.

Yep. I had the Dexcom receiver before getting the X2. Previously I was on a medtronic pump. I don’t think there’s any practical difference between the T-Slim and The X-2 beyond the possibility for over-the-air software upgrades which Tandem hasn’t used yet anyway. I would stick with the T-Slim until the warranty is up.

The software update capability is not new for the X2. The previous pump not only had the capability but it was used and an update was made available.

The X2 continues to have the remote update capability but the first update for the X2 has not yet been released.

One of the big differences between the t:slim G4 and the t:slim X2 is the communication capabilities. The t:slim G4 communicated with the Dexcom using the Dexcom proprietary G4 communication protocols.
The t:slim X2 has Bluetooth capabilities and will communicate with the Dexcom G5 using Bluetooth. This opens the door to the possibility of the pump being able to communicate via Bluetooth to other devices. Hopefully Tandem would continue to take advantage of the Bluetooth on the pump.

That’s interesting–I had the impression it was new from their promotional stuff. In any case it’s not just a good idea but something I feel ALL pumps should have by this point. I mean, if your pump already has an integrated CGM capability, the step to hybrid closed loop is really just a software update, isn’t it? I don’t think there’s any difference between, say, a Medtronic 630G and 670G hardware-wise, so why shouldn’t you be able to install the Hybrid Loop update on your 630 and go happily on your way? Instead you have to buy a whole different pump, often having to wait years for the “warranty” to run out, when there’s no real technical barrier to upgrading the pump you already have, which is absurd. In the case of a G5-integrated T:Slim the remote update means you should be able to go hybrid as soon as Tandem rolls out that capability.

Am I wrong about any of this? Funny thing is I expected to see Tandem making this point themselves when I was considering one but I didn’t come across it in their promotional materials. But it seems like that’s where this is headed–or should be anyway. Not so?

Tandem t:slim X2

Hybrid Closed Loop (HCL)
Launch goal: Late 2018

“Tandem, Dexcom and TypeZero are working together on the integration of their technologies into the NIH-funded International Diabetes Closed Loop (IDCL) Trial. A Tandem insulin pump and Dexcom G5 sensor will be included as part of a blood glucose control system that combines these devices with a smartphone running TypeZero’s inControl hybrid closed loop algorithm. Tandem is also working on development on a Tandem insulin pump that integrates the data from a Dexcom G6 sensor and TypeZero’s inControl algorithm directly into the pump’s touchscreen interface.”


For anybody on the [original] Tandem t:slim or the Tandem t:slim G4 and thinking about upgrading outside of the typical insurance 4 year plan, Tandem has an upgrade program in place currently however it will be closing down soon. This would be the time to decide if this is the best path for you.

“The Upgrade Program is available to eligible customers through September 30, 2017.”


I have heard some people being hesitant to get or continue with the Tandem pump due to concerns over the company’s finances. Tandem just released their Second Quarter 2017 Results and they did beat their forecast by 4 cents per share and shipped almost 3500 pumps during the second quarter. So it does appear they are hanging in and continuing to improve.

More competition in the pump market can only be helpful for all the pump users.

The last thing anybody needs is a single manufacturer left with zero consumer choice available.

I have X2 w G5 and love it. The only isdue is the new case button is very stiff to push. Spent 399 for refurb X2. Almost identical to tslim g4. Led screen is better. Sound is louder. Works the same. Now if they would allow direct (not via iPhone) integration w watch for all functions.

I cut out the plastic button cover on the new case because sometimes it took 4 or 5 pushes to turn on the pump screen. I used an e-Xacto knife and it was easy to do. Since then I read of people just cutting slits on the long sides of the plastic button cover and said that also worked well.

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Bluetooth is nice, but the proprietary DexCom G4 packets were actually ‘better’ (for hacking). DexCom was criminally lazy, they used a TI chip and didn’t even bother to enable the encryption! They just shove your glucose data into the open TI packet and broadcast it without any authentication, device connection, or error checking. Its completely insecure, spoofable, and controllable both for good and evil. I wonder if that’s a HIPPA violation. Consent to share healthcare information must be specific and a broadcast, by definition, is nonspecific. Anyway, the G4 was a completely open data source, the very thing everyone wants for themselves (though problematic if people want to be evil), so it’s obvious that they had to kill that quickly and move to a more secure communication form. That probably tells you everything you need to know about Dexcom’s intentions toward opening things up for everyone with Bluetooth; though, maybe they’ll surprise me.


You seem to be implying that the current Dexcom BLE communications under G5 and/or G6 are now encrypted.

Would you mind providing the encryption method used?

If this is all blatant speculation which is backed up by absolutely nothing concrete than I totally understand.