Last summer, we were traveling in the Southwest and stopped for a meal in a local diner. As a diabetes educator my ears always perk up when I hear someone talk about insulin so when I overheard the waitress talking to a customer about her insulin….
The customer was saying that she had left her insulin in the car when they stopped at an Indian Burial Mound, and that it was very hot in the car. She asked the waitress if she could put the insulin in the refrigerator long enough to cool so that it would be okay. The waitress agreed and shared that her brother did this all the time and the insulin always worked better after it had been cooled down in the refrigerator.
Though I was on vacation, I deemed it necessary to intervene so I introduced myself to the patient and explained that if insulin gets too hot it will not work no matter how cold you get it. I also advised her to not use the bottle which had been heated. She had another bottle in her cooler in the trunk and chose to use that.
I gave the patient my card, we said goodbye and I thought that would be our last contact. Much to my surprise I got an email from her last week thanking me for my advice.
She had evidently taken the used vial from the restaurant when she left and then, testing my advice, used it when she got home a few days later. Two hours after her meal her glucose was at 421 mg/dl and, lesson learned, she took a new bottle from the refrigerator and was able to bring her glucose down to a proper level.
Once insulin gets too hot and loses its effectiveness, no amount of cooling will reverse this. Although we are getting past the hottest part of the year, the same problem can occur if insulin freezes. Patients should be advised of this if possible before vacations in regions with extreme weather conditions, and seasonally.
Dave Joffe, CDE, Editor-in-chief, Diabetes In Control
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