Tandem t slim users

Tandem t slim users…How can you check if the leur-lock section of the pump tubing is ‘loose’? I hear if it’s loose it can build up insulin, then if you go to tighten it, the ‘extra’ insulin can be pushed through (and you’ll GET more insulin delivered? So always unhook from site first then yea?!

My trainer told me to tighten the luer lock each day when it’s disconnected. Sometimes it’s loose and insulin comes out sometimes not. Never tighten it when connected obviously. I also tighten it after filling a new tube before I connect to my inset.