It depends which supplies you are sharing and how you are sharing them. Your machine, sure you can share it, just be mindful to make sure there isn’t excess blood on it to avoid any cross contamination. The test strips, as long as you’re not trying to use the same strip twice, no problem. The needles for pricking your finger, absolutely no sharing the same needle. Letting someone use a clean needle and disposing of it properly, no problem, but using the same needle is a bad idea.
As for what hospitals do, yes, we get a clean needle every time for every patient. Each needle gets disposed of immediately after use and is never used a second time. Most hospitals use needles that are single use only and can’t be used twice to ensure there is no needle sharing.