Tandem t:case for t:slim pumps - BEWARE!

Does anyone have experience with the new t:case for their t:slim insulin pump? I recently purchased one, and every time I try to remove the case from my pump, it forcefully pops the insulin cartridge off the pump and leaves the piston rod of the pump exposed.

Today it did this, and I didn’t think anything of it until checking my BG hours later- it had skyrocketed to 517. I noticed the smell of insulin in my pocket. Removing the case had cracked the cartridge and insulin was leaking in my pocket. I had not been receiving insulin deliveries all day- but the pump was not giving me any kind of error warning message.

Has anyone else had a similar experience?

Yes, I had this happen once with an older Medtronic pump. The crack occurred at the luer-lock connection between the infusion set tubing and the reservoir. I suspect the crack happened when I started a new infusion site/set/reservoir. I had noticed my blood glucose was rising with fingerstick checks but never thought about a possible leak in the system. This was before CGMs were in use.

So I made a few corrections through the leaky pump and, of course, my BG kept rising. I finally discovered the leak by dipping the corner of a tissue into the area of the leur lock connection and saw liquid wicking up into the tissue. It was insulin.

I don’t know if you have access to CGM technology but this incident highlights where CGMs shine. The steady rise of the CGM glucose level will catch your attention sooner than if you use fingersticks or just rely on your physical symptoms.

One of the inherent dangers of using a pump is that it replaces long-acting insulin and you can get into danger of DKA before you’re aware of it.

I know that pumps have fairly effective alarms when pressure in the system rises, indicating an occlusion. But I don’t think any pump warns when there are micro drops in insulin pressure to detect a leak.

Thanks for raising the alarm. When technology works well for long periods, it lulls us into a false sense of security. Diabetes requires vigilance and will rudely disturb us when we let down our guard. I’m glad you’re OK.

Thanks, yes I use a Dexcom. But in a case of “when it rains, it pours,” the Dexcom also failed this morning (after about 10 days of use, however). Yes, the Dexcom would have caught the steadily rising BG. Thanks!

On a side note, I called Tandem to report this issue with the pump case and they kept asking why I removed the case in the first place. They reminded me that I can conduct a cartridge change with the pump still in the case. It makes me wonder if they were aware of this problem and are just encouraging people to leave the pump in the case at all times instead.

Yeah, one of my more threatening lows in the last several months happened during the weekly two-hour blackout period for the Dexcom. Glad to read you’re using a CGM. Some people don’t like adding another diabetes gadget and resist using a CGM. I find it one of the most useful pieces of D-tech I use. I would give up my pump before I would my CGM.

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I’m not familiar with the Tandem pump. A picture of this problem would help to illustrate your report.

What is the weekly 2 hour black out for the Dexcom?

By the way, not sure why they have a graph showing that they don’t offer today.
“Promises Promises” seems to be Tandem’s theme song.


I don’t like that steel clip for several reasons, so I’d go for a third party mobile phone case instead.

Right now I am so disgusted with the t:slim pump, I am thinking about finding someone to trade it off to for an old Medtronic. I just went around with support the night before last. I loaded a new cartridge, filled tubing, filled the cannula. Done with it all, two minutes later it forces me to redo the entire sequence. ARRRRGH!

I have a two+ page review of this pump that I need to trim down before posting here. I was going to give it a 5 out of 10, but it’s closer to a 3 right now.

Please take the time to self report the adverse event. I don’t trust Tandem to do it. I’ve reported a couple that are clearly software related and they have never gotten back to me about what they plan to do about it.

MedWatch Online Voluntary Reporting Form

Are you following the Tandem instructions to take the pump out of the case? I actually worry more about testing off the cover for the charging port. Sorry you are having this problem,

When you start a new sensor session with Dexcom, there is a two-hour warm up period when blood glucose data is not displayed. Like many Dexcom users, when the first seven-day session expires, I leave the sensor in place and start a new seven-day session. This new session, starts out with a two-hour warm-up. So, even if you are able to get two, three, or even four weeks out of a single sensor, you still must complete the initial two-hour warm up period without displayed glucose data.

No. I didn’t use the case for mine (older one) It was too hard and awkward. I used spibelts and now I’m using various waste band belts for pump and Dex. My fav now is the flannel softy belt. So comfy and much cooler than anything else. It’s great for sleeping too. I bought some but I’ll also be making my own. I made one softy belt already with cute flannel cats. I’ll make several so I can change them frequently. I’ve tried the pump in a pocket etc. but it always falls out and feels uncomfortable.

Not sure why you even need to remove the new case from the pump once you put it on … isn’t one of the main benefits of the new case that you can just leave it on all the time? That said … I also have a buyer beware warning. I have a t:slim g4 and have used both the old style case and the new tcase. The old style was kind of a pain in that you had to disassemble the case and remove the pump whenever you changed the cartridge, but the clip (though somewhat clunky) was easy and quick to use. I could easily clip the pump to my belt with one hand without having to look.

The new case doesn’t require removal when you change the cartridge. It’s a tighter and seemingly more secure fit all around the pump, perhaps able to provide better protection, so that’s a plus. But I found the new low profile steel clip to be a real show-stopper. It’s much more difficult to clip on a belt quickly and it’s almost impossible to do without looking and with one hand. Additionally, the clearance between the case back and the clip is so small it won’t fit on a thicker belt without using both hands and/or damaging the belt. I finally gave up and went back to the old style case. I would have been much happier with the old clip style on the new case that didn’t require removal when changing the cartridge.

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Your observation about the steel clip is one of the main things I don’t like, therefore will never use the new case. It’s HUGE too. All of my pants pockets have small slits and I keep the pump in my pocket. But I will use the clip when sleeping or jumping into some work shorts to work around the house. The new case is a 100% will never try it deal for me.

BTW, you can remove the steel clip from the new case. Just use a screwdriver to gently pry it up and slide out. Works much better for me in my pocket that way.

Why use a case if it’s in your pocket? Just more weight and bulk.

Don’t want to highjack the thread, but I recently installed the xdrip app so I could continue using my Dexcom transmitter past it’s official “low battery” deadline, and it offers a way around this problem: you can skip the warm up by setting the session start time to two hours previous to present. Wouldn’t want to do that with an actual new sensor, but when you’re rolling over an existing one there’s really no need for the acclimation period.


So maybe this is stupid and obvious and other people already do it but it suddenly occurred to me that there is no benefit to waiting for the actual sensor to run out exactly at the 168 hour mark (7 days times 24 hours). As Terry points out, after the first session, we are going to restart (understanding the G4/G5 sensor is FDA approved for 7 days) as it is our experience that we can get 12 days of very accurate data from the Dexcom sensor. (I know many people get much longer and likely many people stop after the first 7 days - this is just what we found is typical for us both the the G4 previously and now with the G5 - both using the same model sensor.)

As also pointed out, there is a 2-hour warm-up when the sensor is first started followed by an initial calibration. Even though it is the same sensor, the transmitter appears to entirely treat it as a new sensor.

So this has two issues:

  1. The two hour blackout. Obviously some times are better for the blackout then other times.
  2. The initial calibration. Again, some times are better for the calibration then other times.

So as I said - perhaps blatantly obvious. But rather then do the 2-hr blackout (warmup) and initial calibration when potential there is food and bolus running rampant with perhaps wildly changing blood sugars and when we would REALLY like to see the graph and would consider this a bad time to calibrate…

I can cut it off early. (It is not possible to “delay” the stop. The sensor will not cross the 168 hr mark without a restart.) I can STOP SENSOR whenever I want. So this current sensor, I am going to take it down (STOP SENSOR) early. I am going to pick a time on day #7 (or even day #6 - what’s the difference?) when the graph is in range and level and no food or bolus is expected for another 3 hours. Doesn’t always happen but certain times of the day are much more likely for that.

STOP SENSOR. wait 2 hrs. START SENSOR. Double calibration (we really do take two fingersticks to be sure). Hopefully be back online with a good startup and getting good accurate numbers again before we hit the times (bolus/food/overnight/exercise) when we really would miss the graph or not want to calibrate.

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@Tim35 – I like the idea of deliberately picking the context of the blackout period, one without many insulin units or carbs on board. Stopping any seven day session (either first or subsequent session) early does not diminish the ultimate longevity of the sensor. An added benefit of this tactic is that the double fingerstick calibration that ends the two-hour blackout is more likely to be done when BGs are flatter.