I have been told that it can last along time,I use insulin and I used to take Lantus and VERY LITTLE Humalog in fact I just finished a bottle from 2005!! Of course the pharmacist and Dr. will tell you not to use it past the expiration date but I did and I'm fine.You have to,you can't afford to waste it. I think that the reason that the pharmaceutical companies charge so much for insulin is because they know that they can,because we have to have it so we will pay whatever we have to. It's really sad because it's almost like they are taking advantage of our disease.