High altitude and blood sugars

I live at 5280 feet now and find it harder than managing diabetes at sea level. But going up to 8600’ is a whole different matter for some reason. Does anyone have experience with dosing and getting accurate blood sugars at high altitudes? I always seem to run higher and need lots more insulin in the mountains even with extra exercise.
I have also heard that altitude makes testing less accurate. I’ve had diabetes for many decades and usually stay quite level but the mountains have me stumped. Can anyone help?

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I hope you can get an answer as we went hiking up in the mountain and noticed my sons dexcom was way off compared to his blood glucose checks. dexcom told me it should be fine, but we noticed a difference after leaving the mountain.

We live at sea level, and head to the mountains to ski 2x/yr. My daughter (9, Dx’d at 6) runs high the whole time. We figure on the plane, it’s the sitting still for hours. We’ve gotten much better at counting the restaurant carbs, which was surely a contributing factor, too, but the bottom line is that in addition to all that, she just needs more insulin at altitude, even though she’s skiing hard all day. She also needs more in the cold weather. You probably know to be careful in the hot tub — 15 mins. there will drop her 100mg/dl — and hot weather v. cold weather makes a difference, too.

Honestly, I don’t have any advice — just validation that it’s not your imagination. (No insight on the CGM; we don’t have one.)

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Noticed this when we went on vacation to Colorado. Glad I found this thread and realized it wasn’t my imagination. We’re heading to Montana in a few days, so I guess I’ll just expect the blood sugars to skyrocket again.

Hi all. Thanks you for your responses to my query.

It’s been very gratifying to discover that I don’t have some idiosyncratic wacko reaction to altitude. Since I always start getting high blood sugars in the mountains after 24 hours even with hiking and extra activity, I am just going to raise my basal insulin by one unit if I am going to be there for say, a week. Maybe 2 if that’s not enough to normalize things. If I’m going to 8600’ for just a few days, I’ll just increase my fast-acting insulin and won’t be surprised if I run a bit high overnight. That’s my plan to keep somewhat balanced.

I did talk with the Accucheck folks and the Aviva strips have been tested at up to 10,000 feet. He said it is the fine print included in the box. He also mentioned that using control solution might help. I should have thought of that but of course mine is out of date.

My glucose monitor and cgm keep aligned pretty well at altitude as long as the arrow is going sideways. At one point I was using Freestyle strips and they were terrible at altitude.

Best wishes everyone the mountains are beconing, beautiful and definitely worth it. Sally

Hi Sally!

I grew up in the mountains in Colorado and then went to college in Kansas. I definitely noticed that my insulin needs would change based on the elevation I was at. I recommend focusing on your basal/long acting insulin. When I go up in elevation I need more insulin, and when I go visit the beach I need less basal insulin.

Also, you can look up a guy named Will Cross. He has had T1D for a long time and he summitted Mount Everest! He has talked about how when he went up in elevation he needed more insulin, even though he was exercising all day.

As most of you know, there is little information on the internet regarding altitude and T1 diabetes management. Last year I was preparing to hike up Mount Kilimanjaro (19,341 feet at summit) and I decided to do some investigation. I found a couple of articles written by a woman who does research on diabetes in Toronto and is also a T1. She had hiked Kili with a group of five (?) diabetics and the success rate was 0%. I decided to test altitude hiking and went to Park City, Utah last summer and hiked at around 7,000-8,000 feet (above sea level) for a couple of days. I experienced high blood glucose (BG) and my doctor and I set a plan to address this for Kili. It was not very successful as I hit new highs (over 600!) and new lows. Above 15,000 feet little worked. It challenged me physically as the symptoms for high BG are headaches, fatigue and sore muscles. Of course these are similar to the symptoms of hiking up a mountain! Last weekend I was in Park City skiing and was at 9,000 to 10,000 feet. Day 1 was OK, but Day 2 spiked over 400 and my muscles were feeling the effects of high BG. I would like to get some more information together and write up something on the topic that can be shared so other people understand this issue. Let me know if any of you would like to share your stories. Maybe we can assemble enough information to provide a better basis for managing.

Hi David @dbunzel, thanks for your very interesting story - and thanks for this your first post.
I’d be interested to know if these events you speak about happened when you were wearing a pump of if you used other means for insulin. My mountain hiking and skiing was on low New England mountains and I didn’t experience the “highs” you describe.

If you do write about these outstanding endeavors, I’m sure that JDRF would like to have your story for sharing.

I like your attitude and how diabetes will never keep you from living your life fully.


Does JDRF have a magazine or somewhere where this could get out to a wider audience?


No David @dbunzel JDRF doesn’t have a magazine.

The American Diabetes Association [diabetes.org] does have a magazine called Diabetes Forecast, now in its 70th year of publication; widely read. I had been on its “Reader’s Panel” up until January 2018 issue.

The editorial staff has changed since I was with them and I do not have current direct addresses, but they readily available through the link below; see “Contact Editors” near the left on the footer: http://www.diabetesforecast.org/?loc=bb-dorg

David, I hike at a much more modest 9,000 to 13,000 foot range in the Colorado Rockies. Our cabin sits at 8,600’.
I have had diabetes for decades and am generally well controlled with a long acting insulin and fast acting insulin before meals/carbs.
When traveling to 8600’ from sea level, I would stay pretty normal for a day or two and then my blood sugars would begin spiking to the 200-300 range. I coped by increasing my fast acting insulin but that wasn’t a great solution. I still ran high after the short acting wore off. It was always so strange to be exercising hard and still be running in the 200’s.
I finally figured out that there really is an altitude phenomena I needed to factor into my injections. I live at 5280’ now and take 7 units of long acting insulin, (more than I took at sea level). Now when I go up to 8,600’ I adjust my long acting insulin to 9 1/2 units on the second day. This works so much better. My short acting to carb ratio remains the same, and I don’t spike the way I used to do. (Of course hikes require either more food or less short acting insulin, lovely because I can eat that pbj on top of the mountain).
Larger changes in altitude will require different accommodation, ie when I visit my son, it’s only an 800’ altitude increase and I don’t need to make any adjustment.*
My doctor can’t help because everyone reacts differently I have even read tha some people require less insulin at altitude, though I wonder if that is true or just a guess. It would be good to hear about other people’s stories.


Nice to hear it is not just me! I seemed to be OK my first day of skiing and my second it jumped. I have a cousin who is T1D who lived for about six years in Durango. She never quite felt good at altitude. She had returned to flat lands (Wisconsin) and seems to feel better. I assume from your description that you are injecting. I have a pump and so some of the comments you mentioned (long acting insulin) are not easy to relate. Pumps typically use only fast-acting (Humulog) insulin.

You mentioned your “doctor can’t help because everyone reacts differently.” I wonder if there are some percentages or ranges that could provide guidance when people are up in altitude? It confounds me that when I describe this issue, people have definitely experienced it, but apparently no one has done a thorough analysis to better understand this issue.



I too would wish for some sort of scale for altitude, say for the first 1000 ft of altitude climb you need a certain percentage more insulin…for 2000 ft, you need something more. I can say that for me, a 3000 ft increase (after about 2 days) requires close to a 20% increase in my basal dose, not insignificant. I don’t know how that translates to a pump either. I There doesn’t seem to be much interest, judging from google searches. It’s one of those little, but not so little details that us type ones have to figure out on our own.

Here is a weird thing that happened recently. I was in Tahoe during the snowmageddon.

My blood sugars were running quite low, when my son, also type one, mentioned that his were also unusually low. And his coworker with TD1 was also running very low. All 3 of us were taking less insulin for about 48 hours. Perhaps coincidence, but then again, is there some weather factor that affects us all? (I feel like I have to state that I am not a nut job, and don’t think UFOs affect blood sugars). Diabetes is just such a frustrating moving target, I hope someone will figure out more of the unknown factors that keep our blood sugars fluctuating despite all our best effort and technological advances.


Not sure if you are in Northern California, but I live in Cupertino. Maybe we are just more active in northern California. When in Kilimanjaro there were so many things that could have been attributed to either trek issues or diabetes issues. Fatigue could be exertion, altitude, or high blood sugars. Headaches, could be altitude or high blood sugars. When in Kili I had some low lows (32 one night), but I am not sure if it was conditions, overcompensation or what. I used a pump, which makes some of the long-acting insulin hard to relate to. I actually took syringes with long acting insulin (to complement the fast-acting I normally use in my pump) as a back-up in case there were problems with the pump. I had a back-up pump, which I didn’t use, partially because I was concerned that they programming may not have been right.


Weather DOES affect insulin’s effectiveness. It’s not just hot showers and hot tubs that cause BG to drop: hotter weather makes insulin more effective, too.