I keep the vial I am using out (and when it gets low take another out). I put the date it will be 28 days it is out of the firdge on it as the toss date (no I never get there–but ya just never know)
I also do the same for the emergenct novaog pen I carry in my purse…I have had a few vials go bad–some my error (usually forgetting to put the refrigerated gel pack in --gets hot here in Nevada sometimes) or sometimes bad insulin from the go–prob due to the wonderful forced mail order I get for my insulin…diff rant there…anyway–my CDE and ENDO both said cold insulin hurts and doesn’t absorb as well (quickly)