Curious, I’ve done some testing on previously used cartridges & syringes using water and it only gets to 2.5ML at best, then with the tube filing, 2.4ML actual used. I’ve noticed that all, Animas and Tandem X2, cartridges so far do not fill-up to their advertised measurement. Anyone have any insight or has everyone just accepted it? Being on the high-functioning autism scale, it “ticks” me off.
In the same vein, “32 inch” Sure-T’s do not measure 32" in length. They are closer to 29". I complained years ago but no one cares. Crazy. They could have just as easily labelled them correctly
You trying to get me riled up??? 
lol Agree 100%. Guess it falls into the ‘white lie’ category…
I push 3ml into my Tandem reservoirs regularly. I also purge air before filling the syringe with insulin. Not sure if that makes a difference or not.
There is always insulin left in the cartridge after the pump shows empty. You can remove this insulin with a syringe but who know if this is actually a good idea.
Start a class action for all the inches they have robbed you of over the years?
I think the tubing length includes the tubing from the anchor piece to the cannula piece. Kind of stupid because that part of the set doesn’t really function as tubing connecting your pump to the site. I agree with you that no one cares…
I remove the old insulin from the cartridge (when I remember) and then put it into a vial that I keep in my purse. I don’t reuse it although others regularly put that insulin into their next cartridge. The vial in my purse is a backup that would keep me alive in an emergency but is probably not the most pristine or potent insulin. Although I am mostly a happy Tandem user, there is no doubt that it is hugely wasteful of insulin, especially for those of us with low daily doses.
The Tandem cartridge has 20u or unusable insulin left when the cartridge is “empty”. That’s the volume required for the pumpIng mechanism to operate properly. Add the infusion set tubing volume and that will give you the insulin you’ll lose with each cartridge… The volume display on the pump screen is compensated for the 20u dead volume, so that accurately reflects how much useable insulin in the cartridge after filling the tubing.
In my case the 43” tubing requires 18u to prime so that’s a total 38 unusable insulin per cartridge vs. what I load with the syringe. Now that I have a secure supply of insulin via insurance I don’t worry about this too much because I’m able to build up a reserve supply. My endo writes the script for more than I actually use.
No, I measure the entire length of the set from set to reservoir connector. It is 29".
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However, think of how that wasted insulin impacts those who self-pay. I think it’s sad that they designed the pump to waste so much insulin. Personally, I wouldn’t want to mess around with removing insulin to add to a new reservoir. The less introduction of needles into hopefully sterile insulin, the better, IMO. For years I fought a losing battle with infections from using Sof Sets. I swear they had to be inadequately sterilized because I tried everything including swabbing my skin with Hibiclens to be sure it wasn’t something on my skin that was causing infection. After years of fighting swollen, red infusion sites (clearly infected) the problem went away. There are only 3 vectors for infection: 1) pathogens on skin not removed by alcohol or Hibiclens, 2) nonsterile sets, 3) contaminated insulin. NO WAY was it the insulin, #1 was treated to extreme preparation, and that leaves the one variable that I couldn’t control–the sets.
I agree, but then that feeds back into why the heck we have to pay so much for insulin in the US.
I also lost some insulin with my Animas pumps. There will always be some insulin remaining in the reservoir or connections to the infusion set tubing inlet that’s not transferred. I think Medtronics has (or did have?) a reservoir integrated with the transfer tubing. That would help minimize dead volume.
Transfer tubing would also be a good design target for the pump/infusion set companies. In my case quite a bit of my insulin is eaten up in that part of the system. Omnipod is a great product from that perspective.
Frankly I don’t think any of the pump companies anticipated a world where insulin would be so damned expensive. I suspect they might have done things differently if they started today.
Person who labels them 32" obviously male.
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I don’t remember the details, but I seem to recall that a few years ago, there was a lawsuit - may have been a class action suit - about an insulin pump that had a lot of unusable insulin, and the plaintiffs won. I don’t recall the pump manufacturer or much else - my brain must have moved it to off-site storage. Perhaps there might be a basis for action here?
Repeated my initial test and after give it time, deducting the delivered basal, etc. it does seem to be very near, if not 3.0ML aka 300 units available. Problem is with it’s “estimated” reservoir capacity. But spending more time on it, got closer to the 3.0 this last time. Initial attempt I believe I filled the syringe completely which is close to 3.5ML if you do not use the measurements on the side which in a quick experiment using water, I didn’t do and therefore was left with close to .5ML, thus the misunderstanding.
I recently ran into a batch of tslim cartridges, tandem was less than helpful my supplier made it right.