September 6, 1999
Question from Dallas, Texas, USA:
Our daughter is 6 years old, and was diagnosed nearly 2 years ago as type 1. she is on Humalog and NPH. She has 3 shots a day. While I read a great deal about Humalog being able to maintain its efficacy for up to 28 days without refrigeration, we have had at least 6 instances of Humalog “going bad” on us. It is most easily detected when her glucose scores continually increase for no apparent reason and we change out the Humalog to another bottle and her scores come back to normal. The bottles usually have been open a couple of weeks, so they are not close to expiration. The Humalog appears okay by visual inspection. Is there something we are missing? i have found only info saying keep it under 86 degrees and out for 28 days and nothing happens. Are kids that much more sensitive to the quality of the insulin?
It seems as we get newer, more pure insulins, they become less resistant to the heat. There are some studies to suggest that Humalog may be less resistant to heat than other synthetic human insulins.
Although “officially” insulin is stable for 28 days without refrigeration at room temperature, I tell my patients to try and keep their insulin refrigerated as much as possible during the summer months, even if the temperature in the house is below 86 degrees. I am also quite concerned about what happens to the insulin when it is shipped without refrigeration from mail order houses in the summer.
Make sure you don’t keep the insulin on the top shelf of the refrigerator. I’ve had insulin freeze on the top shelf, which also spoils the insulin. I recommend that people keep their insulin in a refrigerated bag in the door of the refrigerator.