Can you tell me how long can "insulin" be stored and still be viable?

In fridge: Hi. Insulin kept in the fridge, prior to opening, is good for years past the expiration date. Remember, the expiration date DOES NOT mean a drug is bad after that date. That's just the date the company that makes the drug presented to the FDA. Once the vial or pen is started, it will be good as long as it's kept in the fridge until it's finished.