I had a few cartridges of insulin that were getting close to their expiry date, so in an effort to use those up, I decided to use them in the pump. No big deal. Except for the fact that I forgot to push the air out of the pump cartridge first. I put in the needle and pushed...that little orange stopper can fly pretty darn far when a cartridge full of air is pushed into that little cartridge Let's just say we will be smelling insulin on the carpet for a few days. Luckily, I did have enough to fill one cartridge!