Tandem T:Slim or Ypso?

I had a pump appointment last week and I’m debating whether I want the T:Slim and Ypso pump. Whichever I choose will be paired with Dexcom G6.

I’m currently leaning toward the T:Slim, but I’ve got a few questions for people who have used either a T:Slim or Ypso pump:

  • What do you like and dislike about your pump?
  • What made you choose your pump?
  • What have you learned or experienced that you wish you’d known before choosing your pump?
  • Have you had any issues that have made you regret your pump choice?
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I haven’t seen the Ypso pump; it’s not an option for me in the US under Medicare.

The things you should consider with any pump that might be used with a CGM is the possibility in the future of alternate CGM sources that work with it, the daily convenience or inconvenience of the pump, and whether the software user interface is one that you can work with.

The main thing I don’t like about the Tandem pump is common to all tubed pumps. Tubing is an inconvenience. One growing problem for me because of progressive peripheral neuropathy is the touch screen on the Tandem pump receiver. It wasn’t bad when I started but it’s getting harder to make changes.

an annoying thing about both Dexcom and Tandem is that they haven’t figured out how to write a secure, standards-based app to run on a generic Android phone. So
they limit the phones that you can install the apps on with full functionality to the small number that they’re able to test. Ironically those phones have very proprietary (bastardized) versions of Android, or are Apple phones.

Imo if my phone is secure enough to do all my online banking and purchasing, then it secure enough to look at my pump dats.

If you can live with limited statistical information the Tandem and Dexcom apps cell phone app are probably good enough for most folks.
Xdrip+ which connects to the Dexcom receiver as an auxiliary display imo is much better as a daily use analysis tool. It will run on any Android phone, unlike Dexcoms app, uses a fraction of the memory and processor load of the Tandem app and has many more capabilities.

My phone, used primarily as a display for the Dexcom CGM, is a low end LG L422 which cost me $30 new -far less than Dexcom’s receiver.

Because I didn’t have a PC I ran Xdrip,+ in parallel with the Tandem app as an uploader for 6 months so my endocrinologist (who never looks at the online data) would have it available to her practice.

When the 7.6 pump update came out and it became obvious that bolus from cell phone feature would be available only for a very few expensive Android models, I bought a very inexpensive tiny Windows 11 PC just to do uploads, and uninstalled the Tandem app.

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Tandem is my first pump ever. It’s less effort than multiple daily injections (MDI) and I never forget it at home. For sleeping and sports I wear it on a waist belt (like a money belt that you’d use for traveling) and the tube isn’t really an inconvenience. I keep it in a pocket otherwise. If I go swimming I take the pump off. Going through airport security I just show it to the guy and they aren’t freaked out about it.

My daily dose of insulin is about 1/3 less than when I did MDI. The auto- suspend when I’m trending low is nice (especially at night) and the auto bolus / auto basal rate increase if I’m going hig is nice as well but it took some time to get settings right and it not “one and done”, I make adjustments to correction factors or basal rate at least every few weeks. My insulin to carb ratio is a bit less changeable but even that needs done tweaking occasionally.

I like to be active. If given up on the “Active” setting - instead I have a different personal profile that I use when I’m biking or kayaking or skiing or hiking or whatever. For that setting I cut my basal by over 50%, and I still often need to take extra carbs.

So I don’t know much about the other pump but I like the Tandem. My time in range is better and do us my A1C


Another T:slim user. I’ve never tried the Ypso, since it’s not in the USA, but I have looked into it a lot since it was SUPPOSED to be here last year, and I’m out of warranty and prepping for my next pump purchase myself.

I’m a medical researcher, so I really did my leg work when deciding which pump I wanted. I spent months reading and researching… Even reading through the MAUDE database where “adverse events” in the US are recorded. I chose the T:slim over the other options because of the unparalleled safety, small size, rechargeable battery, modern feel, and I was really impressed with Tandem as a company and what their pipeline held. This was before there was any pump automation, so I was very excited to see what was coming soon. I was so sure of my choice that I defied my Endo, who was team Medtronic.

I don’t regret my choice for a moment. 6 years later and I know the T:slim X2 was absolutely the best choice. I’m a MASSIVE fan of Control-IQ. I don’t think it’s perfect, but it’s by far the best commercial option available, and the next upgrade for it is going to offer more customization. Speaking of updates… Tandem actually rolls them out fairly often. I’ve been through 4 major feature updates in that time, and a few minor ones. They’re constantly working to improve the product and they really listen to patient feedback. They send out surveys often and it informs the updates they prioritize. Something else I really appreciate is how durable the thing is. It’s got a metal frame, not plastic, so it’s fairly indestructible. I drop it on tile way more than I care to admit, and no problem ever.

There’s exactly one thing I don’t like about the T:slim, the micro-USB charging port. Drives me insane because I usually charge once a week or so in bed, and I’ve never once managed to plug it in successfully in the dark. I really wish they would have used a usb-C connection instead. I don’t mind the actual charging, it doesn’t need to happen often and it charges quickly. I just hate the shape of the plug.

The thing that most people complain about, filling the cartridge and tubing, never bothered me in the least. I think it’s a struggle for people coming from other tubed pumps because it’s so different. The pump mechanism that makes it so safe, also makes it slow and fiddly. But I came from MDI with insulin vials and syringes, so it was no big deal at all. Nearly the same exact thing, except now I stab the cartridge with the syringe instead of myself.

I think the only things I wished I learned sooner were about the infusion sets. I was pretty much just told I wanted the Autosoft 90 sets, but I learned here that there was an Autosoft XC set that is nearly identical, except that it is much easier to connect/disconnect at the infusion set. And the Internet was right! Autosoft XC is so much better than Autosoft 90! And the other thing I learned thanks to social media was how to avoid the dreaded kinked cannula problem that often sends people running to steel sets instead. It’s really easy to pull the Autosoft sets up and off their introducer needle, so the squishy cannula extends past the needle. When you stab it into your skin with no needle supporting it, the cannula just bends in half. It’s like a kinked hose in that nothing flows through. You just really need to handle the sets gently. No yanking the blue needle cover off, but rather twist it until it spins freely and ease it off. Same goes with removing the adhesive backing.

I’ve had a few issues pop up over the years, but none of them were deal-breakers. Tandem has really great customer service. I’ve only had one catastrophic pump failure, their words, and it really wasn’t that bad. My pump lost all it’s data in a glitch and threw an error code. They overnighted me a new pump, but in the meantime I was able to clear the error by restarting the pump. I reprogrammed my basal profile and it worked just fine until the replacement arrived. I didn’t even lose the data since it uploads automatically to the app I’ve also gotten a few other non-critical warranty replacements for things like out-of-spec battery life and one that gave occlusion alarms when it wasn’t even attached to me. I don’t actually think I needed a new pump in either of those cases, the battery was my fault for letting vibratory alerts repeat and I think the occlusion alarms were actually a bad lot of cartridges, but I was always excited to get a new-to-me pump in the mail.

All that said, I don’t think the Ypsopump is a bad choice. CamAPS is actually pretty good. Control -IQ seems to hedge out all other commercial algorithms in the clinical trials, though. It seems to be the enhanced nighttime performance that tips the scales in favor of Control-IQ. If you do choose the Ypso, though, CamAPS is still a great option. The one big advantage Ypso has over T:slim is the pre-filled cartridges. It’s real easy plug and play. I thought the infusion sets would be another advantage, given the multi-directional connector… But the more I read about those, seems they’re not actually well liked because they sit so high off the skin. Then there’s the battery thing, which could be a positive or a negative, depending on how you look at it. I prefer the greener option myself, but know others like having a stockpile of AAAs.


You will hear all the good stuff about the Tslim. I will add what is the one good thing for me. I can sleep with confidence knowing that it would be truly a rare event if I died in my sleep from a way low or way high because of control IQ. So far so good after a year plus. What I don’t like about it. I use a lot of extended boluses for meals. Tslim will not allow me to change their default 2 hour duration and 30 minute ‘now’ settings for my preference so I have to change those at every single extended bolus. That means, for me, about a dozen clicks per meal. I’ve tried to count it but it’s close to that. When in a restaurant with others, that many clicks can feel like a long time. This may be true with other pumps. Don’t know. I also do not like the requirement to stick a chintzy needle point into a firm rubber on the cartridge to try to hit the “sweet spot” from which to withdraw some unknown amount of air from it before injecting the insulin into the cartridge. I have a few times pushed the needle tip a bit too far (there is no gauge, it’s a guess) and bent the tip of the needle which means I have a mismatch between number of syringes and cartridges. I now save one or two good syringes to reuse for those occasions.
And it does take longer to change the Tslim than it does the Medtronic. There are times when this is irritating. But the Dex/Tslim combo is necessary for my particular situation. I have never minded the tubing. Maybe pulled it out by accident less than 5 times in 20 years. I used Medtronic before Tslim.
This is my reality. But I am still using it 24/7.


Thanks for all the great info, @Blueburd, @Robyn_H, @MBW and @pstud123. It’s so helpful to hear user experiences like this.

I sent off an email to the diabetes clinic with my choice: the T:slim! They seem to think I could get it and Dexcom G6 in the next month!

The micro USB connector was aggravating until I discovered cables with right-angle and left-angle connectors. I can insert a right angle micro USB cable in the Tandem socket in the dark because I know which way it should be oriented.

The rubber port cover of the Tandem pump is a bigger issue for me than the plug; it keeps moving and clocking the jack as I try to insert a plug. I hve neuropathy, but what I can do one-handed with my phones, tablets and computers takes two for the Tandem pump.

There’s nothing electrically special about the cables or chargers that Tandem ships with their pumps. They are good quality but limited in capacity and flexibility and are identical except for color and labels with those Dexcom provides for the receivers.

I haven’t used mine since I got the set. I’ve powered the pump one and off applied updates with generic data+power USB cables, never had an issue. I use smart chargers that sense current and shut off as batteries reach their capacity. I carry a coil-retracting power-only cable with a pocket power bank for tethered pump recharging. l have a Y-cord with a USB-C connector, micro-USB connector and a USB-A connector, and a 15 amp charger in my emergency pack. I can recharge most non-Apple portable devices with those.

Most of my micro USB cables are 100% electrically interchangeable- all one model, 2 meters long and black, except the permanent bedside one and my carry-with cablesthat are white. My solution to plug orientation is a dot of nail polish on one side of the connector and a similar dot on each device. (High quality plugs have a symbol on the “flatter” side of the connectior, none on the other side. But they are hard for me to see or feel.) The dots work ok if I have enough light to see what I’m doing, but I have to look.

I looked forward to USB-C cables until I discovered that its just a plug shape, the connectors have chips in them that limit what they can do and what they can be used with. Lightening connectors are physcally the same, but electrically different.

Now I have to deal with 6 different identical-looking 6 foot USB-C cables that I had to label and must pick through each time to interconnect equipment. Colored replacements are on back- order.

I sleep with confidence. I didn’t when I was on MDI and using a BGM 4x/day. If I die in my sleep the pump won’t be the reason. I starting having no faith in the pump and did what I needed to to survive any possible CGM ir pump failure.

It wouldn’t matter whether had Basal IQ, Control IQ or what mode it was in. The pump could stop pumping and my basal profile and before I sleep levels are good enough that the worst case would be my BG rising, not falling.

I don’t have enough FOB (food on board) at bedtime to cause a severe rise or so little that it would fall out of range. I’d need to have diarrhea or vomit and I know how to
handle those safely.

So If I die while sleeping, it will be from a stroke or heart failure, and in any case, I won’t have an BG -control issue to wrest with afterwards. Sounds like heaven to me.

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I am switching from Medtronic to Tandem. With Medtronic I’m currently using Mio Advanced sets and they work great for me. When someone from Tandem called me yesterday to go over my order he asked me what sets I wanted. I told him I wanted the one that looks like the Medtronic Mio Advanced with a single button on the top of the inserter. I thought he said that was the Autosoft 90, but now I can’t find my notes. From what you’re describing it sounds as if the Autosoft 90 is similar to the original Mio sets that come in a round disposable inserter with the tubing wrapped around it inside.

I have Googled the names of Tandem’s sets and the only pictures I see are of the boxes which don’t look like anything!

Sorry, but Tandem doesn’t have anything similar to Mio Advance right now. I wish they did, since it seems so popular. Just the ones like the original Mios in the UFO-looking dome. Both the 90s and XCs come in that same packaging, but the connector is shaped differently.

If you don’t like the automatic inserter, Varisoft sets are the same soft cannula, but they’re manually inserted.

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I’ve been using a tandem pump for roughly 10 years. It is a good pump, but I tend to get a lot of errors that make no sense. I do not like the way they are infusion sets connect to the tubing. It should be one simple tube without that hard connector. It should be easier to fill the cartridge. You should not have to poke the needle into it three or more times to fill the cartridge. The control IQ is great.

So I poke once into the center of the white dot, withdraw on the plunger to remove the approx 0.1cc of air that is there, inject the 150 units of insulin that will suffice for the next 3-4 days being careful not to re-inject the air, and I’m done.

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That’s what I do, also. But I read @Twilson8 's comment as having trouble finding that “sweet spot” that feels hollow and receptive. We all know when the syringe just doesn’t feel like it’s in the right area, but it’s a hard sensation to explain.

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Yes, I agree you should not have to poke it three or four times to withdraw error, and or add the insulin to the cartridge but you do.

The new tandem will use a syringe cartridge like the Medtronic and will be controlled by phone and wireless charger. Those were my top 3 issues with the tslim.
They added phone bolus but none of the other options can be changed by phone.
The mobi will not have a screen so having your phone nearby is going to be required

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Is Varisoft like the Medtronic Silhouette? That’s what I used for the first 16+ years but I could only insert in my abdomen. I was getting many insulin flow blocked alarms so I finally switched to Mio Advanced. They allow me to use a lot of new sites. Eventually I’ll give the angled sets another try but I’d rather leave my abdomen alone for awhile.

I had to look that one up. Yes, Varisoft looks just like the Silhouettes , except Taken doesn’t have a crazy harpoon gun looking inserter. You just stick the needle in manually.

I did insert the Silhouettes manually. I used the harpoon the first time I tried the set and instantly regretted it.

@MBW I just wanted to come back here and say that those who have excellent vision and steady hands can poke once. But not all older ones of us are that fortunate. I rarely can just ‘poke once’. I think I am aiming exactly center of that small white rubber or rubberish target but more often than not I hit off center and must try again. It should not be necessary to withdraw air, for one thing. That is an unnecessary client step. No reason for air to be in there. And no reason to push insulin blindly into a hidden bag. What were they thinking? Being more difficult is not the way to be ‘different’ from the other company!

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That’s why the mobi won’t have the same kind of cartridge it’s more like a Medtronic cartridge, but I haven’t actually seen it only going off of images