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From Trinidad, West Indies:

Can insulin go bad, even before the expiry date on the vials? My daughter, type 1 since 12 months old, takes such small doses of insulin that the vials of insulin last for months. On a few occasions her blood glucoses started to rise abnormally and after switching to new vials of insulin her blood glucoses became controlled again.


Once insulin is opened and being used, it is best to date it. Discard it after two months if keeping it refrigerated, discard it after one month if keeping it at room temperature.


Additional comments from Dr. Quick:

In general, the expiration dates on pill bottles and insulin bottles should be considered to be the best guess of the manufacturer of how long the product will remain fully active under routine circumstances. If the product is stored in abnormal heat or cold or humidity or bright light, the product may become less effective before the expiration date, as you have already found out. (With other products, there's some concern of the development of other active molecules that have adverse effects if the product is used beyond its expiration date, but that's not a concern with either insulin or diabetes pills.)

There's been an additional concern for insulin: if the bottle of "clear" insulin has a cloudy appearance or shows "frosting" on the inner surface of the glass bottle, or has white lumps in the liquid, don't use that bottle: the insulin has crystallized, and the fluid that's drawn up into the syringe has less active insulin molecules. Such a bottle should be returned to the pharmacy; it can be exchanged for a new bottle.


Original posting 29 Aug 1998
Posted to Insulin


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Last Updated: Tuesday April 06, 2010 15:09:00
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