My T-Slim leaks insulin :(

I got my T-slim a couple of months ago and was SO excited to have a smaller pump I could wear close to my body so I wouldn't have dilemmas with wearing different dresses and skirts! But now I am sorely disappointed and thinking about switching back to Medtronic. I am convinced the cartridges are leaking insulin. I first experienced this problem in October after I had a HORRIBLE rash that looked like cat scratches and itched like crazy. The rash was exactly where I had been wearing my pump next to my body. I thought it was the soap I was using or something. But every time I wear the pump next to my body, I break out in a rash exactly where the tubing/cartridge was. My husband speculated it could be insulin leaking. I didn't think too much of that suggestion until I noticed the odor. My endo also said insulin can irritate the skin, which is why most people have a red mark after changing sites.
The leaking seems to happen towards the end of the life of a cartridge. I think the little part where the tubing meets the black cartridge bends and starts to loosen. It definitely happens after I remove the case from the pump, because that causes it to yank a little bit on the lure lock. But really, I am not rough with my pump. It should be able to withstand this!
I also notice my BGs are a little bit higher at the end of the life of the cartridge. I noticed this at its worst in October when I had the monster rash.
I have been wearing the pump in a case on my waistband and the tubing in my pocket or somewhere that is NOT next to my skin. Until yesterday, I wore it in my bra and guess what? I have a horrible rash today and will probably not sleep well tonight because it is itching so badly. I'm sure it will look like cat scratches tomorrow, because that's how it always appears.
Has anyone else had this problem?! I am going to call Tandem tomorrow. I pray it's just the boxes of cartridges I received. Maybe some different lots of them will not have this problem. I really REALLY wanted this pump to work out for me. :(

Sounds like you might have gotten a few bad boxes of cartridges. I would call Tandem they are great about replacing them really quickly.

The odds of multiple cartridges being defective in the same way, even within a particular batch, should be very, very low, albeit not zero. You mentioned yanking, can that be avoided? Are you perhaps putting pressure on your tubing in other ways? If this is happening to you, and not other people, it's of course possible that you are getting a series of bad cartridges and the other people are not, but it seems more likely that there's something about the way you're using them that's causing this (which is not to say that some sort of defect might not also be contributing).

Can you ever actually see this leaking insulin? If it's enough to irritate your skin, it should be visible. For example, look at the tubing connection as the pump delivers a bolus, and toward the end of its life, and ideally after you've noticed that rash that you think leaking is causing. Hold the pump in various orientations, including the orientation in which you think it's leaking.

Is it possible you're allergic to something else in the pump or case? What exactly is touching your skin? The plastic back of the pump? The plastic case into which the pump slips? Something else?

I hope you figure this out! You should definitely be in touch with Tandem, they will go out of their way to try to help you (because they'll lose you as a customer if they don't figure it out), and in my experience their customer service is great.

Things to try:

Call Tandem and request a new batch of cartridges. Give them the lot number on yours and tell them how many you have had issue with. They will replace them. They are an excellent company in all respects and will try their best to help you figure this out.

Make ABSOLUTELY CERTAIN that you have the Luer Lock on your infusion set fully tightened. As in, you can't possibly turn it another millimeter.

When you fill your cartridge, make certain to clean the top where you filled it. Both on and around the little white rubber part where the syringe goes in.
Many times there is a small bit of insulin that is left there when you remove the syringe.

After you have filled your cartridge, run the tubing fill process and pay close attention to the Luer Lock portion to see if there are any visible leaks.

The above should narrow down whether or not it is an issue of bad cartridges or infusion sets.

Use Cortisone cream for itching. (use it sparingly)

Did you always carry the pump loose and right up against your skin?
Did you always carry it in a case or pocket?

The tubing should NEVER leak from where it attaches to the cartridge. The fact that you say that it is definitively happening when you remove it tells me that you are pulling it from the Luer Lock to remove it from the pump unit. DO NOT DO THAT.
You should always use the little black plastic key that came with your pump. If you have lost it, ask Tandem for a new one(or two). That key ensures that you are properly removing the cartridge and not putting unnecessary pressure on the actuators that are responsible for dispensing insulin doses.

If your BG readings are higher on the last day that means that you should either change your set a day sooner or account for the fact that your insulin is losing potency and shift your dosage.

Sorry if it appears that I am asking obvious questions but your statements in your post are rather disjointed and difficult for me to make clear sense of.
Please do not take offense as I am in no way trying to marginalize your issue or belittle you. I am only trying to get a clear picture to try and help you better, so I hope you understand.

All the best,
- Mario

I'm curious, when you say you wear your pump touching your body, what do you mean? In other words, if we're just talking about the pump itself, how does it stay in place alongside your body? Or do you mean inside the case with the clip?

I just replaced my infusion set and experimented with trying to pull the tubing out of the old cartridge. The tubing is extremely robustly attached to the cartridge, the tubing material starts to dramatically stretch and almost break before it releases from its cartridge attachment. So it seems to me that absent defective manufacturing, it would be very hard to do anything to create a leak in that area.

Mario mentioned not using the tubing to pull out an old cartridge, and while that makes sense--sort of like using a power cable to pull out a plug, a very bad idea--this shouldn't cause leaks because by definition the cartridge is used up and about to be replaced.

I hope you figure out what's going on, because it seems really strange (and I'm sure must be frustrating).

One other thought: Are the rashes close to where your infusion set is located? Because a localized rash is often an indicator of an allergic reaction to the insulin you're injecting. Is it possible you switched insulin, for example from humalog to novolog, when you started the t:slim? That could explain new rashes, because perhaps you're allergic to the new insulin. If this is indeed the case, you should be very mindful of more systemic allergic reactions, because those are potentially dangerous.

Thanks for your help!
I talked to a customer service guy from Tandem today. They are sending me a new box of cartridges and I'm going to send them my existing box back so they can test it.
Yes, I thought of all the things you've mentioned. I started cleaning the cartridge and entire pump with an alcohol swab after replacing the cartridge, I am super gentle with it, and I remove it with the plastic key. (But thanks for that info on only using the key- I didn't know that it had to do with pressure) I also check the luer lock after refilling and I check it for leaks frequently. The odor of insulin is pretty obvious right where the black part of the cartridge ends and the tubing begins. There is no strong odor near the luer lock. I don't pull the cartridge out from the luer lock. What I meant was that, when you take the pump out of the case, you have to pull the case apart sort of forcefully to get it to release. This usually means the part of the case that passes through the tubing will run right into the luer lock. Because of that, I either do NOT wear the case at all, or I only wear it when I know I won't take it off until a tubing-change day.
The customer service rep speculated that the problem could have been something with shipping. He wondered if the batch of cartridges I'd gotten had been in the heat or something. I got them in September, so it's possible, I suppose. He said with the existing ones left in the box I have, they should be able to figure out if there was a problem with the supplier/shipping.

Yeah, I know what you mean- thanks for your feedback. I have used Humalog since it first came out and I never noticed any skin problems with it. Only a small red dot when I remove a site, which I understand to be normal. I told my endo that I wondered if I had a skin allergy to it, and she said sure, it's possible, because the mix they use to preserve the insulin contains chemicals (or something like that). Hence the red dot you get when you remove a pump site (and I don't get one from my Dexcom sites). She gave me a bottle of Novolog to try, even though she told me they are really pretty much the same. I have been using Novolog for the past month and have had the same issue.
I definitely do NOT pull the cartridge out by the tubing- I use the plastic key. The only time the tubing gets pulled a little is when I remove the pump case, and I only do that when I am removing the tubing to change the cartridge. I also clean the cartridge with alcohol, especially the little white rubber part where you fill it from a syringe. I just recently started doing that, hoping it was just some leftover drops or something.
I haven't actually seen drips or noticed any wetness on the pump or cartridge, but then again, I wear it inside a pocket these days, so my clothes could be soaking it up. I definitely notice the odor of insulin, though.
When I wear the pump close to me, I wear it in my bra or inside a pair of running shorts that has a small special pocket. Anytime the cartridge with the beginning of the tubing is next to my skin, I get the rash.


If you still have issues after they get you the new batch of cartridges, give them a call and ask them if it is possible for them to send you a loaner pump.
You can ship them yours once it arrives and they can fully inspect the pump for any leaks in a controlled environment.

Sorry I couldn't be of more help in this and I truly wish you the best. I understand how frustrating it can be to try and figure out.

- Mario

I have read where some tighten the lock every day. Unlike other pumps the lock is not stationary and has some movement. I've never had this problem before because I turn the lock so tight that I can not unscrew it, but some only do it finger tight.

Every pump I have ever owned I was trained when I disconnect to shower to check the line for any catches, and inspect the lock before reconnecting making sure it is tight. Never tighten the lock while you are connected because you can actually give yourself a small dose of insulin. I"m not that sensitive that it will hurt me but know some that even a fraction of insulin unit will drop them.

I hope this helps.