1-2-3 GO: convince me to switch to t-slim

UPDATE: I started using my new t-slim 2x one week ago and I LOVE it. I am thrilled to have current technology—touchscreen fits my style! I will start on the Dexcom G6 on September 10 so I can begin using the Basal IQ on the t-slim. This will be the first time of using a CGM after 37 years of finger sticks and 3 years before that peeing in a cup. So looking forward to it.

I am going to put my paradigm 523 (circa 2011) to pasture soon. I am 95% ready to get a t-slim but need a bit more convincing from actual users. Please convince me, happy t-slim users. (Yes, 1-2-3 is a bit of a pun).

I have no experience with a tslim, but I find your “95% there” reason enough to proceed! I’m sure users will move you that last 5%. :slight_smile:

Depending on the version number, this may be a valuable model to the Looping/OpenAPS community.

I switched from MM to Tslim in April and I’m very happy with it. The infusion sets took a few insertions to get comfortable with them, I found I had to lower basal rates across the board and extend my IOB from 3 hours to 4 hours.
I like the simplicity of the touch screen, entering carbs is easy without all the scrolling needed with the MM.
I’ve only needed tech support once, but they were responsive and professional. When I asked for a couple samples of a different infusion set, they set me an entire box.

This is my first pump, so I don’t have any real world comparison, but I did a LOT of research before making my choice. I even had to fight for my t-slim against medical advice, just because the Endo had never worked with anyone besides Medtronic.

My deciding factors, in random order that I thought of them as typing:

  1. Size. The t:slim is tiny. About the size of a credit card. At a whopping five foot tall, size does matter to me. It can be very discreet if you want it to be, but it looks good enough to show off also.

  2. Touchscreen. I know not everyone likes this, but I do. It makes the user interface variable to future updates, and I find the current interface very user-friendly. Plus, it feels modern. I think that subconsciously leads to greater confidence for me.

  3. It’s rechargeable. In my home, we’re very energy/waste conscious. We drive electric cars, have solar, hydro, and wind power energy systems in place, and live in a homestead. In this day and age, there is zero reason to be throwing batteries away. I’ve never baby sat it to see how fast it charges, but it’s always back to fully charged after the half hour it takes me to shower, dress, etc. I rarely let it get below 40%, though. Depending on how hard I use it, a single charge lasts about ten days, but I don’t have a computer, that may wear a little harder. I usually charge while I’m disconnected anyway, but you don’t have to. You can charge while you’re sitting somewhere, or from a battery pack on the go. I got a tiny “lipstick” battery pack when I first got the pump, just because I was paranoid, that’s small enough to tuck into my bra with the pump and I never need to worry about a charge again. The reality is though, I rarely ever worry about charging anymore.

  4. Superior algorithms. This one gets down to the nitty gritty. Tandem is really good at partnering with other people who know what the heck they’re doing. They work closely with the looping community and what algorithms THEY use in their closed loop systems, as well as TypeZero. This is one of the main reasons why Medtronic was able to get faster fda approval for their 670. They follow the “if it ain’t broke…” mentality, and piggy backing on old, previously approved therapy means a much faster approval. Tandem’s breaking new ground, which takes time to process, but yields a superior product in the end.

  5. Customer service! Tandem has been amazing in this department. I literally couldn’t hope for more. When my Endo told me that Medtronic was the only company that represented the area, I very hesitantly called Tandem hoping this wasn’t true. They were only too happy to assure me they would would find support for anyone who wanted to use their products, and that location was no issue. They immediately went to work getting the Endo trained on their system and interface software set up. I had to do nothing. I didn’t even have to make the three hour trek back to the Endo. Tandem even offered to set up virtual pump training over the internet, if they couldn’t get a trainer into my remote area quick enough. When I asked for more detailed info than the reps were trained in, I was even sent details of the medical trials.

That was just my first experience with their customer service. I’ve contacted them a few other times over the last year and a half, and it’s always been pleasurable. It takes only a few button pushed to confirm you’re an existing customer before you’re quickly connected to a HAPPY representative. Seriously, they’re always upbeat and pleased to be of assistance. No crabby techs who get yelled at consistently and drip venom into the phone line.

In contrast, it took seven weeks for anyone higher up the food chain at Medtronic than the sales rep to call me back about detailed questions I had. By that time, I had already decided to move forward with Tandem, and had been using the x2 for three weeks.

I do have one major complaint about the pump, which I’ll detail later. In addressing the issue with customer service, I was actually put in contact with various members of the design team. Apparently I was using the pump in a way most people don’t, and presented them with a new problem they hadn’t considered in the design. I was told it was too late to include any alterations for this problem in the next update, but that it would indubitably be included in the following one. THIS earned an insane amount of respect from me. They’re actively listening to their customer base.

  1. Software updates! How cool is it to not have to wait 4 years or so for your current warranty to expire every time there’s a big technology advance? I don’t get to play with all the features they’ve rolled out this way yet, since I don’t have a cgm, but I did the first update just to try it out. It’s pretty much as simple as plugging the pump into The computer and following on-screen instructions.

  2. Has been completely hassle-free thus far. There wasn’t a lot of user feedback online when I was searching. I found a few mentions of constant, recurring occlusion alarms, and complaints about the fill process, and little else. In a year and a half, I’ve had exactly two occlusion alarms. Both of which were resolved just by detaching and reconnecting at the infusion site.

  3. Supporting the underdog. Let’s face it, nobody sets out to take on pharmaceutical giants like Medtronic or Johnson & Johnson (animas was still in the game then), unless you vehemently believe you can build a better product and do better for the prospective market. It would be capitalist suicide, otherwise. I really think these are the guys that deserve our support because their goals are more closely aligned with our own. We’re not just a dollar sign not a stock point to the underdog. They’re small enough to still see the individual people driving the business.

Things to note/negatives:

  1. I can’t speak about omnipod. They took themselves out of the running for my business because they can’t manage to ship a box all the way to my home. The trial pods I tried to sample all expected me to drive nearly 2 hours to a sort facility, even though FedEx, UPS, and USPS all come directly to the front door.

  2. Apidra doesn’t play nice with Tandem pumps. It tends to crystalize and cause occlusions.

  3. The t:connect software requires newer versions of Windows or Mac. There is no Linux support at all. I know this won’t affect most people, but as a Linux user (it’s superiorly more secure and customizable), I find this disappointing. I get around this by running a “tiny box” version of Windows inside Linux

  4. I have one MAJOR complaint about the X2, and it has to do with the bolus calculator. It’s generally very easy, once you have the pump programmed, you just tell it your BG and amount of carbs, and it will calculate your dose for you. There’s an option to add extended bolus, if desired. Now, I often pre-bolus while cooking, without testing yet. I’ll test when I sit down to eat and enter carbs into the calculator. USUALLY, insulin on board is subtracted from the dose calculation… But there is some magic combination of blood glucose and time lapsed, which causes the X2 to sometimes ignore insulin on board. This was intentionally designed into it, and it pisses me completely, because I can’t imagine a time when my insulin on board isn’t reducing my glucose. I suppose it’s intended for post-prandial glucose that hasn’t been absorbed yet, but still… I had a lot of lies I didn’t understand my few weeks in the pump because of this. It was essentially double-delivering my pre-bolus a second time. I sometimes see this when I’m going hypo, too. I’m apparently the only fresh of nature that likes to enter my carbs when I correct, because I have a tendency to eat more than I need. It’s those times when my brain is fuzzy that I have to manually calculate my dose. Math is easy… But not when you’re hypo! I still wouldn’t consider this a deal-beaker, though. No pump is perfect, yet. And I suppose this is a moot point for those fortunate enough to have a cgm.


Sorry, the coloring is off because of the bad cell phone picture. In real life, the top and bottom rows are bright white, and the middle two are greyed out. Generally any item that requires additional insulin is in white, and any item that requires reducing the calculation (such as below target BG and insulin on board) is in red. In this example I entered a blood sugar of 102, which required a tiny correction, and 25 g of carbs. I already had two units on board, which SHOULD appear in red, but the calculator is ignoring insulin on board entirely. It still wants to deliver the full 2.27 units for carb, despite the fact it already knows I have 0.46 units too much insulin already working in my system. My sugar would quite literally bottom out if I hadn’t learned to check and override these bad calculations. This only seems to happen when I’m very near my target, though.


I had MM for 14 years and then switched to t-slim two years ago. I have been really happen with it, most especially with the Dexcom integration. I like the sleek design, the touch screen, the t:connect software, and the USB charger. Any frustrations have been very minor. As far as CGMs go, though, the Dex is so much better than the (admittedly older) MM sensor I had and never used.

I have two complaints.
The Dexcom G5 has to be CLOSE to the pump for the pump to get signal.
When using Fiasp, the pump acts similar to aprida for crystalization for me if I try and run a cartridge for 4 days or more. I would have to say that somewhere on the 3rd day I am seeing a faded affect of fiasp. Not consistently enough to warrant going to 2 days per cartridge/infusion set.
I would like to see an adjustable screen brightness, but I think that is just being picky.
Other than that, I LOVE IT!
I can enter my BG, carbs and bolus in a VERY short time, and still be confident in what I am doing.
I wear mine in a SPIbelt, and don’t take it out of the belt to bolus, etc. I see through the belt to use the touch screen without issue in all normal lighting. In BRIGHT sunlight I will need to find shade, or take it out of the spibelt. Then it is plenty bright.
And no one even knows what you are doing when you are dosing with it being a small touch screen, let alone when I have it in the belt. Totally incognito!