Answered 8/21/2014 by Samuel Grossman, BS Pharm, Pharm.D, CDE
Once an insulin vial is taken out of the refrigerator and opened it will expire in 28 days. Whether the insulin is in a pump or sitting on the table it will not make a difference. It is important to write the date that the insulin vial was opened and to remember that an expired insulin will not function well after 28 days in the pump. A possible first sign of an expired insulin vial is high glucose levels despite no change in your level of activity or the amount of carbohydrates you consume.