Ok so we give our cat u40 insulin. My neighbor ran out of syringes. They use U100 insulin and syringe. I've looked online and can only find a converter for using u40 insulin in a ,U100 syringe. I guess he gets 1/2 a unit a day. Is there a way to convert that or maybe it would be better to let them use a dose of our U40 insulin or something. Any ideas of the best way to tackle this? Thank you.