Does hot summer weather change your insulin usage?

I’ve never done well with heat and have generally avoided outdoor activity when the temperature hits 85-90. With diabetes, I feel worse in the heat and have to make more insulin adjustments to avoid lows. Anybody else?

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Being outdoors in the heat drastically reduces my insulin needs.

Funny how heat can effect us all so differently.

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I know @Michel said his son @Kaelan had a drastic SPIKE in BG due to sunburn, so was already aware that “the outdoors” can wreak havoc on people with Diabetes…I’m learning so much about what to watch out for in Liam and it’s all most appreciated! <3

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Temperature can affect insulin absorption. Higher temperatures will increase the absorption rate and bioavailability of insulin. Heat causes blood vessels to expand. So reducing your insulin during exposure to heat makes sense.

Personally I have not noticed it too much, I guess because I am used to it.


There are some thoughts that PWD have a harder time regulating their body temperature when exposed to heat.

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I think the difference in activity level between summer and winter can have a pretty big effect.

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Being out in the heat all day lowers my insulin needs, even if I’m not particularly active. If I’m even somewhat active (think standing/walking around all day), the effect is dramatic. I once forgot my morning shot of Lantus (split-dosed) when I went to a music festival in weather that was in the 90s and humid, and I figured I’d need to compensate with lots of extra humalog during the day. Nope—it actually worked out perfectly, suggesting a decrease in basal of about 50% was effective. Also, I had maybe one beer that day, if that (it was a while ago, so don’t remember that perfectly), so it wasn’t effects of alcohol consumption.

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Thanks for the link to the article, @Eric.

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As luck would have it, I just returned from a one week trip to the heat/humidity in NJ with the worst BG I’ve had for quite some time . This was a family reunion with my 96 year old parents, so lots of sitting and also some mental stress caused by the stubborn high BG. I did not vary my I:C ratio or basal due to some wishful thinking that I could correct the highs. I also switched to new insulin pens partway through the week with no improvement.

My CGM plots below say my insulin need increased (i was there 6/30 to 7/6). I suspect this was due to inactivity. The 14 days prior to the trip reflect an active daily routine in great Seattle summer weather, avg BG 106, 89% in range.

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In recent years I haven’t noticed much of change in insulin usage, but when I was on MDI, my BG seemed to go up rather than down.

Was yours a result of the difference between active and not-active?

The stubborn higher BG (including overnight) seems to be solely a symptom of the inactivity. Forgot to mention that days were spent outdoors on the shaded back porch and nights in my air conditioned hotel room; the daytime highs were at a humid 85-90 degrees.

However the jury is stll out as I just got back to my normal routine today. My experience has been a few days are usually needed to get my BG back in the mood to cooperate after a bad spell.

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