Cold and diabetes – antifreeze in the blood?

Homeostasis. Thermoreceptors, thermogenesis, blood-glucose. A lovely vocabulary of regulation. When it’s cold, you shiver; when it’s hot, you sweat, and when you’re diabetic, you begin to understand the sheer amount of energy it takes to keep a human body at 98.6 degrees Fahrenheit all the time.

Now that winter’s here, it’s time to explore the mysterious relationship between diabetes and cold weather. Most of the people I know who have Type 1, also have strong opinions about what cold does or doesn’t do to one’s sugars, but the science behind each opinion remains murky for now.

I can tell you, anecdotally if not scientifically, that the feeling of being cold might mask the feeling of being low. Both feel like a subtle cellular panic, and sometimes when I’m out in the cold I don’t realize how low I am.

One time in college, I went sledding with my friends. In order to reach the best hill, we had to park on one side of a frozen lake and walk across. Wind-kicked snow swirled around us, “reducing,” in that wonderful meteorological phrase, “visibility.” It was probably between 10 and 20 degrees Fahrenheit, and I’d brought a can of Coca-Cola for sugar.

Being from Georgia, I had no idea what cold, serious cold, could do to one’s blood glucose level (BGL). Simply by walking across the lake (an eerie and lovely experience, as strangers on ice skates appeared out of the mist and swept past us), my BGL dove to the 40s mg/dl (2.2 mmol/L). Then I realized I’d forgotten my coke in the car. My friend had to hurry back over the lake, drive around, and run across a snowy golf course to bring me sugar. The coke fought the insulin but lost, and we had to drive off in search of more sugar.

Researchers do not fully understand the correlation between blood-glucose levels and temperature. Heat can apparently either lower blood sugars or make them go high. Cold weather supposedly raises A1Cs, but what about getting low from walking across a lake? Perhaps people stay indoors and fail to exercise when it’s cold, and it is this inactivity, rather than the cold itself, that contributes to higher A1Cs?

Whatever, the case, experience has taught me that being active in the cold makes me go low. It makes some intuitive sense: in low temperatures, the body needs to metabolize glucose in order to keep warm, which makes blood-glucose-levels drop. However, no scientific consensus exists.

The relationship between diabetes and cold gets weirder.

Apparently, the colder a place gets, the more likely its inhabitants are to develop Type 1 diabetes (T1D). Diagnosis rates in countries like Norway and Finland are much higher than diagnosis rates in equatorial countries.

In fact, according to one Canadian physician, it’s possible that T1D once helped human beings survive deadly cold.

Dr. Sharon Moalem hypothesizes in his book Survival of the Sickest that diabetes may have been an evolutionary adaptation that helped humans stay warm during a sudden, terrible ice age 12,000 years ago called “The Younger Dryas.” Dr. Moalem’s theory rests on the principle that sugar acts as a kind of antifreeze.

He mentions the Wood Frog, an amphibian native to Canada and the northern U.S., to support his thesis. The Wood Frog has developed the ability to concentrate glucose around its heart and lungs in order to survive extreme cold. Their skin does freeze — they go “clink” when you drop them— but the concentrated glucose in their vital organs’ cells keeps them alive until their skin can thaw (National Geographic).

In other words, Dr. Moalem’s suggests that diabetics living through The Younger Dryas would have been less likely to freeze to death because of their sweet, syrupy blood.

Sweetening one’s own blood wouldn’t be a sustainable evolutionary maneuver, of course: untreated hyperglycemia eventually kills. Still, Dr. Moalem’s theory offers us the compelling image of some prehistoric diabetic becoming the lone, frostbitten survivor of a killer cold snap, and living just long enough to pass along his or her mutated genes.

Such theories are too slick and entertaining to immediately convince the scientific community. Today the relationship between cold and diabetes remains the victim of empiricism’s favorite bogeyman, insufficient data. So I cannot tell you with any degree of certainty what frosty days will or won’t do to a diabetic’s delicate blood chemistry, only that going out into the cold can provoke something unpredictable.

I can, however, offer some practical advice. Stay hydrated. Check your blood glucose level often, even when your fingers are cold. Bring enough sugar on your snowy adventures to drag you up from a hypoglycemic hell. Bring a friend who can help you out if you need it, one who would run across a frozen lake for you. If you have a vial of insulin with you, keep it close to your body to keep it from freezing and becoming useless.

Diabetes might have helped one of your ancestors survive a night of wretched, spine-curling cold. Probably not, but who knows? It’s something to think about while you go sledding, wait for your car’s heat to turn on, or walk to work through a hush of snow. We don’t understand the relationship between cold and diabetes, but in due time, the data become sufficient. Until then, be careful out there.


I guess that I always assumed that there was a viral component (like the flu virus) that was more prevalent in cold areas, leading to higher incidence of type 1 diagnosis during seasonal cold. But, it sure is interesting. I sorta wondered if higher glucose doesn’t provide the energy to survive temperature ‘extremes,’ which might help include the Egyptians and the Saudis higher incidence of diabetes. But, the one type 1 Saudi that I know attributes it to ‘inbreeding,’ which might also help explain higher than average genetic likelihood. Cold weather populations might have been kinda isolated.

I bike for exercise, and I like to keep going through the winter, at least when there streets/paths are clear of ice and snow. Normally a 45 min. ride at a good clip will drop my BG 30 points or so, other things being equal. But it’s a distinct thing that, if the outside temperature is below about 30°, my BG goes up instead, and not just a little. My theory is that at some point your body says “Hey, no sane person would be doing this just for exercise, he must be trying to escape a polar bear!” and fires off my adrenal system.


Thats interesting, DrBB. I get really high when I ski, but I figured the adrenaline was from just the energy output. Its useful to know about your experiences.

That’s not far-fetched. So-called secondary epigenetic rules – cognitive algorithms of sorts – make all humans, on some level, afraid of things like heights, fast-moving water, thunderstorms, and other dangers to our early ancestors. Including, possibly, racing down the side of a steep, snowy slope. We may not feel any danger, we may not recognize it consciously, but the adrenaline response kicks in. I’ve seen my Dexcom line go up just from watching those things on TV when the camera flies off the edge of a cliff. These little danger signals may be constant, further adding to all the things that influence BG.

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I’ve always wondered about the genetic component of type 1 diabetes. When I was a kid, and my endocrinologist said all type 1s are diagnosed as children (which is not true, but that was the information I had at the time) I wondered how I met kids at camp who had all of their uncles also having type 1 diabetes. I thought, “if, before 1922, we all died before we reached maturity, how did we pass on those mutated genes”. Now, myself, I have 1 great grandmother who developed type 2 in her 80s, and nobody else, so if my diabetes is genetic, it was passed down through many generations in recessive genes. Inbreeding might explain some of it (colder climates are more prone to inbreeding because of the difficulty in traveling historically, and I know for a fact that the Welsh side of my family suffers from inbreeding because I know our history, and my dad was born with 11 fingers and 8 toes), and if my great grandmothers brothers or sisters died from type 1 diabetes, I don’t think that knowledge would have been passed down, but it’s a question that I’ve never found a truly satisfying answer for.

Presumably, since blood sugars rise due to adrenaline, there must be some physical benefits to having high blood sugars during a crisis, regardless of diabetes. If that’s the case, then maybe there was an evolutionary benefit to diabetes when everything was a matter of survival. 10,000 years ago, I imagine the average human had substantially less food and more stress than today, and they had children earlier, so there may have been advantages to their high blood sugars that allowed them to procreate more easily.

Interesting. I was dx in 1959 in Calif. Have lived in the NW for almost 50 yrs. I have never noticed a difference in glucose levels when it comes to cold weather. I also am not a big outdoors person, so maybe that is the difference?

I am probably inbred on my fathers side since they were from a very isolated part of the US and although we can’t be sure because there weren’t any Dr.s there most of my aunts and uncles died as toddlers. It could have been one of many childhood diseases that they weren’t vaccinated against or diabetes. I think I was a combination of hereditary (based on the admittedly sketchy anecdote from my dad of all those babies dying suddenly) and then catching the flu.

As for cold messing with my BG’s I don’t usually notice any difference when I go out in the cold but heat will always sky rocket my BG’s. Some of that is dehydration but it can’t be all of it. I usually just drink water like crazy and replace my electrolytes as much as possible to combat it.

I am all over when we ski. I have gone low by lunchtime but usually high at lunch. I eat the same breakfast, ski the same runs. I have tried to be consistent to get a handle on it, but haven’t so far. I guess I will just have to keep trying. :wink:

I am off to Korea tomorrow for a week, where the climate is -2 to -16 on the flat, and we are going to the hills. This is colder than I have ever experienced in my life. Seeing I now live in the Philippines and before that in Queensland Australia.

I guess I am going to have a personal science experiment on the impact of cold on my personal diabetes experience. I shall certainly need to be sure my insulin doesn’t freeze else I shall not be able to eat for most of my trip!

I hope our accommodation is central heated, else I shall also face the problem of how not to freeze insulin when ambient temperature is below zero (I guess this would mean keeping it on my person, but not directly against my body?)!

Can one even finger stick and get blood when one’s fingers are frozen (aside from the ouch factor)? I have a libre but find that it gets progressively less accurate over the 14 days of use (seems I have immune response to the inserted sensor).

I lived in Korea for 18 months, and I was coming from California, and Korea is definitely cold in the winter. I recommend layering, and then keeping the test kit and insulin under the top layer, or under the second to top layer if it seems really cold. I didn’t notice that many blood sugar variations due to cold, but I had so many variables to take into account, I might have missed it. Gloves are a good idea, and your fingers and test kit won’t freeze in the minute it takes to get them out and test. However, don’t underestimate the cold. My brother came from California, saying, “I’ve been snow camping”. When he got off the bus, he was blue, but I had long John’s and gloves with me because I knew he wouldn’t be prepared.

Koreans are super, super nice though, and they all love learning English, so they will bend over backwards if you do have a problem.

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I’ve had meters freeze a couple of times over the years and once you warm them back up they still work. You might want to pack your insulin in a insulated pack which will help to keep it from freezing.

I’ve been T1 for 43 years. For the 1st time, this past summer ( very hot in France) my insulin needs dropped by 30%. They returned to their previous level in September. Now, it’s getting colder, and my needs are rising. I’m fairly active (hiking, skiing) and while hiking can make my bs plummet, snow shoeing doesn’t. Skiing makes it rise. I have been told that heat improves micro circulation of the blood, thereby ameliorating insulin absorbtion. That would explain a lot.

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That was so well written and really interesting. Thanks for that. Merry Christmas from Canada.

What a fascinating, even helpful and practical subject that is well-written to boot! Thank you. The only question that remained for me was how you felt being out on that lake. What made you check your BG? Were you symptomatic or just vigilant? Or both? (not always possible to be vigilant during hypoglycemic episodes).

ETA: I now remember how you mentioned the cold can mask hypoglycemia. Was that true in the case you mention?

I have been T1 for 73 years, and I am 79 years old. My body temp is consistently a degree less than the 98.6 that it used to be. My temp varies during the day. I need a blanket over my lap during the day, but not during the late evening. I sleep at night with a single sheet over me, while my wife has a very heavy blanket. My BG is not high at night, but I am very warm then. I tend to be somewhat cold in the daylight hours, and very warm at night. This is not due to a change in my BG levels.

Thyroid, Richard?

Hi @Willow4, my endo had my thyroid tested. There is no problem there.

korea ia great. last day now. temperature tosay is -7 to -14. found out im much more sensitive to fast acting here when its cold. My meter doesnt like the cold either and displays error.