Tandem pump question - New user

Hi Everyone,
I just started using a tandem t:slim a few days ago so I have lots of questions. First, is it common practice to change the infusion site along with the cartridge? It’ll be 3 days for my infusion site this afternoon but I still have 115u left in my cartridge. I really dont want to waste insulin and wondering if they can be changed independent of each other? When you disconnect pump to shower do you have to put that little plastic cover on connection site or not? Third, do you ever give an injection via pens if BG remains high 2-3 hours after a meal, or is something else done to address high? Thank you in advance.

I do sometimes start a new set with the old cartridge. Don’t know if it’s advised against, but I have not noticed any issues.
I personally find that no amount of insulin will help lower my numbers if I don’t drink some fluids to wash out any ketones - even if there aren’t any it seems to help (go figure).
My endo gave me a flowchart showing what I should do if I am not able to get my numbers down - including how long to wait and when to disconnect and switch to injection. You should not inject on top of insulin from your pump as the pump will have no way of knowing how much extra you have - additional insulin on board - which will interfere with its calculations. Waiting for the numbers to normalize can be like watching paint dry - it might take 4 hours to even start to see movement but you should confirm with your doctor how long to wait before adding any additional via the pump. If you find yourself frequently going high after eating you may need to change your carb ratio: your doctor will advise you.

Hi Diane, I also change out the infusion set and keep using the same cartridge and have never had any problems doing so. I normally fill my cartridge when it gets below 10 units of insulin left. This is usually every 4 - 5 days, depending on what I’ve eaten and how much exercise I get.

Pam K.
T1D 57.11 years and counting!

Hi Diane,
My son is 13 and has been using the tslim since about November of 2021. If we have insulin left at the end of the 3 day infusion site, we withdraw it from the cartridge and use it in a new cartridge. I am sure this is not the advised way of doing things, but considering the cost of insulin that’s how we roll. We’ve also been known to go 4 days before changing the infusion site. If there is enough insulin in the cartridge to get us through another day, especially if it seems to be a good location for the site. The tslim will show the total daily insulin used, so my suggestion would be to check the total and use that to calculate how much insulin to put in the cartridge. Concerning your question about the plastic shower piece…we started out using it religiously, but the little thing is hard to not lose, so he hardly ever uses it now. We’ve not had any issues without it. Also for the pen injections with high “unresponsive” BG…yes we have resorted to using an injection a couple of times, however stubbornly high BGs have also been an indication of a bad infusion set…bent cannula or the like. If you decide to use a needle, please do so with caution, and finger check BG several times. The pump won’t know how much insulin is actually on board, and you don’t want rebound lows. So calculate carefully on how much you give and keep a close check on the BG. I hope this helps. Good luck!

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Thank you all so much for the info and sharing your experiences. I sometimes feel like its more trial and error than any kind of exact medical protocol. I appreciate your info.

Lilly says that insulin effectiveness degrades after being in plastic for as little as a handful of days. Remeber that if you constantly have lots of leftover insulin you only have to put in what you need you dont have to fill the cartridge full. I wanted to prefill cartridges and was told absolutely not a good idea by my endo.

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it’s not a common practice to put twice as much insulin as you need in the cartridge for 3 days . Insulin stored in the plastic cartridge starts to lose potency after 3 days of normal environmental conditions .
There’s no way to maintain sterile conditions of the cartridge umbilical.when you detach tubing. Waste the insulin once and next time fill it with a closer estimate of what you need for 3 days. (3*TDD +45 units) . If you have a little more than you need, you could stretch the third day, a little less, shorten it.

You can put a cover on the cannula when you shower, but the seal is washed as you shower. It makes as much sense to put a cover on the loose tubing end to prevent bacteria from landing on it and being pushed through the cannula seal.

Hello Diane, I am using the Medtronic 630 pump. I change sets every 3 days. If I go beyond 3 days I start seeing higher BG’s. I think that is caused by emerging scar tissue. I have places on my body that I cannot use because of permanent scar tissue. I am type 1 for 76 years.
I use 1.7 ml of insulin each time I change sets, that is always more than enough for 3 days.
I never use the plastic piece when taking a shower, but some pumpers do.
If I have an unusually high BG I use an injection into my bicep muscle. Insulin works faster in muscle tissue. Your pens could be used for that purpose.

Thank you all so m much for your replies and info. As a newer T1 I have soooooo much to learn.