Climate Change BG Rollercoaster

I live in New England and twice a year experience 8-15 days of BG rollercoaster. During the rest of the year, can hold BG 100% TIR (Time In Range) , SD (Standard Deviation) of 18 mg/dl or better within a BG range of 55-150 6 AM to 10PM and BG range of 55-130 between 10 PM and 6AM for 30-day periods.

During two 2 periods I drop to between 96%-97% TIR and my SD goes up to 20.

The 2 periods are in the Fall season when we go from hot/warm Summer days to cold mornings and in the Spring when we go from cold Spring days to warm Summer morning days. The earliest indications are that in the Fall, there is a need to wear a light jacket in the morning to feel comfortably warm and in the Spring, it is the period when the sweater comes off.

The only other time climate change affects my BG more than temporarily is following a long flight (at least 13 hours) and going from an airplane-controlled climate to a very hot and humid climate like to Asia or Africa from the US or Europe. The effect then is short-lived at only about 4-6 hours but still noticeable and needs to be taken into account with adjusted insulin dose after last meal before landing.

Temporary climate changes would mostly be times such as taking a shower with a wide difference between ambient temperature and temperature of shower water and the effect goes away within 15 minutes.

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I know several people that say their numbers go up in the summer months from heat. But it’s not a temporary thing, it keeps going higher with each higher wave of heat throughout the summer? I have never noticed a problem with me and until last year we had hot summers and some very high temps off and on. I always wondered that maybe one of the differences was I have always stayed well hydrated, I literally go everywhere with either water or tea. But I haven’t heard of it because of cold changes.

I do get a radical change with a hot shower, I can go up 60 points within 20 minutes and I feel yucky as it’s happening. This is in the am that it’s so bad. So if I have to take a shower in the am, it has to be lukewarm on the colder side. That does not come down on its own. I have to take extra insulin. It starts to abate in the afternoon but as the day goes the effect is definitely lessened. Sometimes at night I have even dropped. I have to think my DP plays a part in this.


I have always experienced these seasonal shifts in basal requirements. Many years ago, when they’d sometimes land me in hospital with DKA, my endo, who specialized in female hormones, told me that males also have hormonal cycles, though they’re rarely as obvious as female ones. It makes some sense that the metabolism would adjust as the body prepares for what it expects to be a period of downtime/scarcity or more activity/food.

I do notice a seasonal shift in my insulin needs. Generally in the fall I need to raise my rates and ratios and in summer I need to drop them. That’s in addition to the monthly hormonal shifts in insulin needs, which are massive.

It’s funny, though. Even your “worse” control is very far removed from my definition of “rollercoaster”. :slight_smile:


Just as a matter of comparison, I take 20 minute hot showers, normally, and my BG rises just about exactly 1 mg/dl per minute in the shower so typically 20 points, however, shorter shower, less rise

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Both heat and cold affect my BG in rather extreme ways. I live in Northern Idaho, so it doesn’t actually get terribly cold in the winter or super hot in the summer, but it does get hot and dry in the summer. When it is really cold out (and I spend a lot of time out in the snow, walking or skiing), I tend to run low. When it is really hot, I tend to run high.

Do you suspect that your lows are really from the Winter cold or from the extensive time and extra work effort your body experiences due to exercise. I used to ski a lot but gave it up due to always running low during that activity. Now I don’t exercise much at all during Winter and after my 8-15 day adjustment in the Fall, my BG’s flat line again.

I tend to exercise a lot pretty close to 12 months a year. Part of it is where I live, it’s just a pleasure to be out. I walk or bike to work every day, I hike on the weekends, and I climb, ski, or snowshoe when I have the time.

The lows in the winter I’m absolutely convinced are because of two factors:

  1. we get a lot of snow, generally, so it’s always more work to get around; and
  2. I’m convinced that my body just spends more energy in the winter to stay warm.

Both of those factors cause, to my understanding, an increased release of muscle glycogen but also an increased uptake of blood glucose for storage as glycogen. For me there is no more effective way to (naturally) lower blood sugar than emptying my muscles. I dislike summer heat, and I suspect my increased BG in heat is mostly about stress (and consequent liver dumps).

If I had a CGM (which I don’t) with enough precision, I suspect that in winter activity I’d see a marked uptick in BG (from beginning of “exercise”), followed by a steady lowering and then a persistent low. It’s the same thing that happens to me when I go to the gym for a high intensity workout. I start high (liver dump), and then end up in a long low (due to muscle uptake).

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I’ve never heard of any of this! Thanks for posting - I’m getting ready to move somewhere with real seasons for the first time in my life and I had no idea it could affect my blood glucose. Something to look out for.

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Something to look out for but not worth worrying about in advance. It can certainly easily be dealt with, especially if you are on a CGM.


Are you guys sure that the observed changes are due to changes in BG as opposed to the meters being temperature-sensitive? I remember that Abbot had some kind of temperate control in their first CGM to increase accuracy. I notice that my observed BG goes up during a hot shower and falls back after cool-down. If a shower would increase my BG, why would it go down after cool-down without extra insulin?

Mine are definitely exercise and temperature related, since I don’t have a CGM. The lows (and sometimes highs) will persist for hours after activity, and has been consistent from the time I was diagnosed. I’m just very sensitive to fluctuations in insulin and blood glucose. THe heat might be psychosomatic, since I always seem to look for an excuse to sit inside and do nothing if it’s over 80F outside :rofl:

That happens for all of us. My CGM shows 1 mg/dl climb for every minute in a hot shower. I normally shower 20 minutes, hence 20 point climb. This is not a meter effect as I don’t take my Contour Next One meter into the shower but do wear my CGM sensor. If I fingerstick just before and again after shower, my fingerstick very closely matches my CGM.

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You don’t shower with your Contour meter? You’re missing out


About 1 year ago My Contour meter fell out of my pocket in the garage getting out of the car and I did not notice. Could not find it anywhere but when I drove out a little later noticed that it had rolled out in line with my front wheel and sure enough drove right over it. Interestingly, the meter still worked, sort of. The only issue were parts of the LED lines in the BG number were no longer showing so tough to guess BG sometimes. I went to Walgreens and picked up a replacement meter and ever since then treat it with great respect.:yum:

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My mind was going to an inappropriate place. I’m glad you show your meter the love it expects.

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I have had type 1 for 40 years. I have never noticed any before, after or during shower BG changes but i have never tried paying attention to that either. When i was diagnosed, at age 9, i didn’t have all of this fancy equipment to be able to check so often. However, since i was a teen, i have noticed seasonal changes. I usually need less insulin for a week or so in the spring and fall. I have never heard about hormones influencing my insulin needs but that would make a lot of since to me. I also have a degree in zoology and i know many, many animals have hormonal changes by season, so why not humans too? I would be very interested to find out more about this.

Yes, I noticed a long time ago that seasonal changes (not climate change) affect my insulin needs. I change my settings in spring and fall… not by much but enough to make a difference.