I've been told by our ped endo that insulin is only viable for 28 days after opening the vial. After the 28th day, we need to throw it out. Do you all stick to this guideline? Do you use the entire vial? In your experience, is there any degeneration of the insulin's effectiveness after 28 days? Or is this kind of like the cosmetic industry's admonition to throw away your mascara and buy a new one after so many months because it might "go bad"?
Replacement of insulin is not really an issue for us cost-wise, because our insurance covers it. But, they will only allow one vial each 28 days, so we don't have a back-up on hand if something happens to the open vial (drop/break/loose/overheat/etc.). Do you keep an "old" vial on hand for backup? Or am I worrying about non-issues?