Just A Few Things About My t:slim

Since starting back on the t:slim, I wanted to make an effort to try to solve some of the “issues” I had with the system. Not that they’re major issues per se, but things that sort of bugged me.

The biggest thing was how it just didn’t seem to deliver insulin or, for whatever reason, didn’t seem to do well in heat. That, I think, was all attributed to those bad cartridges I had. Since changing out to new ones, I don’t have issues with unexplainable highs any longer. As far as my whacko BG’s, that seems to now be fixed, and I can joyously use the pump (knock on wood) with no problem.

My next thing was more of an annoyance, but it bugged me even still. Now, I have figured a work-around for it. It was the insulin level calculation. If you’re new to the t:slim, you will notice that if you fill it with, say, 250 units, the pump will only register 200 in the history section. PicFrame (5)If you fill your tubing and cannula, you’re likely to only need 18 units for that and then maybe a half-unit for cannula fill. That, coupled with that the pump automatically hides 20u, you’re still left with 10 units unaccounted for. Every time, I would assume that I should be showing 212u by the end of the process, but I would inevitably only show 200. That part bugged me to no end…. it seemed as if 10 units was going unaccounted for each time. So, what did I do? I figured out it’s calculations. The pump takes what you fill it with and subtracts 50u and then whatever you use or don’t use during prime/fill is just left as extra, apart from the 20u cushion. *NOTE: The following is NOT recommended by Tandem and I’m only telling you what *Ido, not what YOU should do. If you do, do it at your own risk.* So what did I do about it?? Since I want my pump to read 200u at the end of each fill, I put in 250u from the syringe. I let the pump start it’s prime and get it’s bubbles out, all the while, I have my Inset set turned upside down in the cap of the Inset top to catch extra drops. I continue to let it prime until it’s primed out 28u exactly. I have tried going to just 25u and it still registered 200. I went and let it fill all the way until the pump stopped (I think 29.8u is the automatic stop?) and then it registered less than 200, so for some reason 28u is the magic number. Now, the problem is, you have 10u of insulin that has pumped out into this Inset cap. You can either choose to discard it (which is what you would have done anyway if you had left it in the pump) OR (and again, this is NOT endorsed so if you do this, you are doing it at your own risk) you can draw it back up, and place it in an empty insulin bottle that you’ve removed as much as possible of the old insulin out of. This may not seem like much, but if you change your cartridge out every 3 days, by the end of the month, that’s 100u of insulin you can put into the pump and use at least 50 of. I wouldn’t recommend putting it back into the bottle you drew it out of initially just because it *may* have been contaminated going through the pump cartridge and tubing, but maybe keeping it in a separate bottle marked somehow could help you save on insulin. Granted, doing that may not be worth it, but if you’re tight on how much insulin you get per month, it may help. For me, I just let it fill to 28u to calm down my OCD brain. I haven’t yet tried saving the insulin yet, so I have NO idea if it will affect the insulin’s potency, though I can’t see how it would anymore make it contaminated than when you draw up air and put it into the bottle of insulin.

Speaking of priming, there’s a big thing about the bubbles. For me, I simply use insulin that has been out since it was opened. I never put it back in the fridge so I never have to worry about it warming up again. For me, this caused LOTS of champagne bubbles every single time. Now, I slowly draw it up, get rid of as many bubbles as possible, and when I fill the cartridge, I don’t just press the plunger in as fast as it will let me. This causes bubbles again. Think of it this way, as a visual representation. When you’re filling the syringe, if you get a bubble and press all of the insulin back into the bottle fast, you get a lot of bubbles in the vial, then it’s almost impossible to get the insulin back into the syringe without getting bubbles back. BUT, if you push the insulin back in slowly to get the bubble back into the bottle, more than likely you won’t get bubbly insulin in the vial thus getting bubbly insulin into the syringe when you pull back. Applying that same logic to filling the cartridge, filling it sloooow and steady reduces the amount of bubbles I get each time. I know this is crazy, but sing the birthday song if you’re filling it with 300u. Since filling it at about that rate, I’ve been able to reduce the amount of bubbles I get when priming.

My other pet-peeve that used to bug me (and still sort of does) was that the system does not reverse correct. If your BG is below your target but above 70mg/dL, the t:slim does not subtract out insulin from the bolus so that when your BG normalizes, you should return to your target. Instead, the calculation brings you back down to where you were. The problem with this is that it also does not subtract out IOB.PicFrame (7) So, say you’re 79 and with 1.2u IOB and you’re going to eat a 27g carb snack. You know that if you don’t subtract out that IOB, you more than likely will go low. I didn’t want to start doing this, but honestly, for the time being until they fix it, it makes the most sense. If you enter 69 as your mg/dL, it WILL subtract out the IOB and also subtract out a correction amount :PicFrame (6)

See the difference? If I had let it calculate based on just my BG of 79mg/dL, I would have been given a calculated bolus of 2.73u. However, by simply fibbing and saying my BG is 69 mg/dL, the pump corrected and suggested a dose of 0.9u. That’s a LOT less insulin to say 1u lowers my BG by 56 mg/dL, and if given the dose based off of my actual BG, that was 1.7u too much (approx).  So, as a suggestion, if you’re at risk for going low based on your IOB, enter a 69 mg/dL or whatever number that is close as possible under 70mg/dL that you’re comfortable with. Again, I don’t *like* doing this just because I can’t stand to have incorrect data in my records, but until they fix this, it’s really all you can do apart from doing your own math and changing the suggested amount (which I used to do, but now I’m too lazy and don’t care).

This is all I can think of right now, but it’s a lot in terms of how I’ve learned to live peaceably with my t:slim… okay… well, I’ve always LOVED it, just not everything about it. Keeping these things in mind help me get past what I don’t like about it and just simply see it for what I do like about it.


1 thought on “Just A Few Things About My t:slim”

  1. I never used a Cozmo pump, but everyone who did raves about how it handled IOB and everything like that. My understanding is that a lot of the T-Slim people are previous Smith Medical employees, so I wonder why the T-Slim seems to be in the dark ages on how it handles lows and IOB. Fortunately someone like you understands what is going on, but what about people who don’t have a clue?

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