I have used insulin several times in the past and I love it. My question is how long after the expiration date is it really effective for??? It cant go bad in 1 month, but I have a full bottle that I purchased and then tore my bicep so it has sat in my fridge and expired over a year ago. Is it still worth a shit?? Maybe its lost half it effectiveness?? I cant imagine anyone being able to go through a bottle in a month anyway. Its Humulin R BTW.