I have been using Apidra insulin that is expired by almost a year. I know it sounds like a stupid question, but how bad is that? I got quite a lot of bottles for free before I had insurance and I can't stand to see them go to waste. Plus even with insurance, new bottles are expensive.
Beyond the expiration date on a vial of insulin, the manufacturer cannot guarantee the sterility of the product, nor can it guarantee the same level of potency. It may be okay to use an expired product shortly after the expiration date, but after that there are no guarantees. Think of it like milk: sometimes it will be good after the expiration date, at other times it will be spoiled. Though insulin won’t “spoil,” the proteins in the insulin can break down and not work as well. In general, people find that when they use “old” insulin it does not work as well as insulin from a new bottle. If you find that your blood glucose levels are getting higher, it may be because of using the old Apidra. I know it’s hard to waste insulin, but if it is a year out of date, it is best at this point to just throw it away and get new bottles. When you do this, don’t be surprised to see your blood glucose levels go down.