You've carefully calculated the right dose based upon what you're eating and how much you're exercising. But do you know exactly how (and where) your insulin should be stored? A lot depends upon the temperature, experts say.
In order to work effectively, insulin should be stored at anywhere from about 45 to 75 degrees, says Dr. Steven Joyal, author of What Your Doctor May Not Tell You About Diabetes: An Innovative Program to Prevent, Treat, and Beat This Controllable Disease. Freezing insulin is not recommended, however.
At room temperature, a punctured insulin vial will last anywhere from 7 to 40 days, depending upon what kind it is, says Olha A. O'Quinn, Ph.D., CDE, a diabetes educator at Saint Vincent's Hospital in New York City.
"Once the bottle has been punctured, you can store insulin at room temperature," she explains. "In your pocket or purse is fine." Since the storage times of insulin do vary, it's best to carefully read the leaflet that comes with the insulin. Some of the longer acting insulins last for more than a month after being punctured, O'Quinn explains. The easiest way to know how long insulin has been open is to date the bottle as soon as you open it.
Insulin vials and cartridges that you are not using yet should be kept in the refrigerator, she says. Once you start using them, you can leave them out for a week or longer, she says. If you are carrying a vial with you when you travel, you may want to invest in one of the small coolers or insulated bags that the diabetic supply companies sell, says O'Quinn.
When you refrigerate insulin, the temperature of the refrigerator should not be below 36 degrees since freezing destroys the insulin activity and it won't be usable any longer.
"It's not that there is a danger of using it, but it won't work too well if the insulin freezes," explains Joyal. "Even after it is thawed, previously frozen insulin won't work well."
And, he adds, the same holds true if the insulin gets overheated.
The key to proper storage is to avoid extreme temperatures, says Bonnie Juston, health services manager at Barton Center for Diabetes Education in North Oxford, Massachusetts.
"If you go hiking in the desert, you can't just keep insulin in the backpack," she says. "You would want to keep it chilled in an insulated bag."
You may also consider a reusable cooling wallet, which is handy for keeping vials, pens, and pumps cool. These wallets have a liner filled with crystals. After you immerse the liner for about 10 minutes in cold water, you place it back into the wallet, along with the insulin. The process of evaporation acts as the cooling agent and can keep insulin cold for up to 48 hours, according to the MayoClinic.com.
