What happens to insulin when it is exposed to heat? For example; 150-180 degrees for six to eight hours? Is it safe to use, is it just ineffective or does it get toxic somehow?

You’ve asked a good question, especially when you live in a hot desert. Insulin should be stored at room temperature. When it is exposed to high temperatures as you describe, the insulin can become damaged and less potent. You may see some changes in the color or texture or nothing at all. Sometimes the only way you know it is damaged is by watching your blood sugar go up for no good reason. The insulin companies have listed the temperatures that are best and most state “room temperature” which we interpret as less than 86 degrees.

KS
Additional comments from Dr. Tessa Lebinger:

I find that during the summer, insulin starts to spoil faster than during the winter when stored at room temperature (patients call with unexplained high blood sugars that come done when they buy new insulin). I usually recommend that insulin be stored in the refrigerator as much as possible, and taken out and allowed to warm up to room temperature for 10 to 15 minutes before injection. (It stings less and works a little faster when given at room temperature). Although “officially” insulin is stable at room temperature for up to a month, I find that, during the summer, it sometimes tends to spoil faster if not kept refrigerated when not in use. Be careful, however, not to store the insulin on the top shelf. Some refrigerators are so cold on the top shelf that the insulin freezes and spoils in the refrigerator! I usually recommend that insulin be stored in the refrigerator in a small insulated bag in the door or on a lower shelf.

TGL