Stay cool, my friends.

Okay, so obviously, I need to post this. If only to remind myself that insulin becomes useless once it reaches a certain temperature.

About a week and a half back, I had to toss out my reservoir with something like 65 units of insulin left. My site was working well for a few days; then allofasudden, my glucose kept climbing up. Over the 300 mg/dL mark. In the middle of the day, which is very odd for me. When I got home from work, I changed out my set, and wouldn’t you know it, before long, my BG came down into the upper 90s – low 100s.

This sequence of events didn’t surprise me too much: It is summer in Baltimore, and baby, does it ever get hot and humid here. Add to that the fact that our air conditioning unit finally gave out about a week earlier, and it’s no wonder I couldn’t keep the insulin in my reservoir cold.

Fast forward to this week. Again, I have a site that’s working very well, for about 5 days (yes, I often go longer than 3 days… so sue me). And we had a new A/C unit installed about a week ago. I go to bed overnight sitting at a pretty good 96, and I had a granola bar for a snack right before turning in, so I wasn’t worried about going low. I got up for a minute about two hours later, and a quick check of the Dexcom unit showed 124. About what I expected.

Then, about 3 a.m., the Dexcom starts beeping. That loud, “you’re high, you’re high” beep. Now it says 224 mg/dL. Great.

By morning, I was at 266 mg/dL. I took the reservoir out of the pump, and it certainly felt warm to me. I must have been sleeping right on it all night. Those reservoirs aren’t always the easiest things to look through, but what was inside didn’t look like normal insulin to me anymore. So I decided to throw out 70-plus units of insulin this time and change everything over. Today was a sensor change day too, so it was a double blessing while I was trying to get out the door to work.

Novolog, the insulin I’m using right now, has a tolerance up to 86 degrees farenheit (according to their website). By the way, Glucagon is only good up to 77 degrees farenheit. Above those temperatures, bacteria living in our insulin start to break down the protein inside our vials, insulin pens, and yes, pump reservoirs. Also, according to a Mayo Clinic blog post, “Heat can make proteins like insulin harden, which increases the potential for infusion set occlusions”. They also recommend tucking in the tubing instead of leaving it out and exposed to the heat (which is what I’ve been doing).

Man, I used to love summer. Now the hot weather gives me one more thing to consider. I know I will be much more careful through the next few months.

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  • Karen  On July 16, 2013 at 12:11 pm

    Ugh, this is probably about the only BAD thing about summer. Hope your insulin is faring better lately.


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