Hi
@ChrisY1981, I don't think metformin would be a good idea as it's not a substitute for insulin and won't help if you're high. I would ring 111 if you're in the UK and see what they advise, they may suggest an out of hours pharmacy or going to a walk-in centre for a prescription in the morning. As you've had your tresiba hopefully you won't be high, can you use your dad's blood tester until you get a replacement?
It's always a good idea to have back ups for everything - insulin pens, blood testers, finger pricker etc etc