All this debate on the best DIY refrigeration method [for insulin] omitted a key question: What is the real shelf life for insulin, if you keep it properly refrigerated? Thanks, – J.E.C.
JWR Replies: Definitive data is available in this diabetes journal article: How Long Should Insulin Be Used Once a Vial Is Started?. The article notes the following from a pharmaceutical manufacturer for refrigerated, unopened bottles:
“Lantus was found to meet stability criteria for at least 24 months when stored between 36 and 46°F (2 and 8°C) (Aventis, data on file). Accelerated stability testing at 77°F (25°C) revealed a slight loss in activity by 9 months. Testing at 95–102°F (35–39°C) for 1 month revealed an increase in impurities without loss of activity. Lantus should be stored in a refrigerator to maintain the labeled expiration date. In the absence of refrigeration, unopened vials of Lantus should be discarded after 28 days.”