Greater insulin resistance in winter?

Since this is my first year with T1 I wanted to ask: do folks get greater insulin resistance in winter?

The past month and a half or so my ratios have shifted from approximately 1:10, 1:15, 1:18 (on exercise days) and 1:9, 1:13, 1:15 (on non-exercise days) to more like 1:7.5, 1:11, 1:14. I gave 4u for 32g this morning and had to take a hot shower and walk a mile and a half to settle down in the 90s. Doing that in fall would have tanked me. I’d say I’m giving 1-1.5u more per meal right now. There’s some research on this that isn’t strong or conclusive, but I wondered if others have anecdata.


I haven’t looked on the internet, but anecdotally I would agree on the observation that you need more insulin in winter.

From my anecdotal perspective, I wouldn’t call it insulin resistance; i would call it hibernation. I’m not as active and so the insulin has to work harder since there’s less exercise to help.


Yes, it is a fairly common thing. Our body is designed to store more in the winter months. And people are generally less active in the winter months.

But aside from the general population, also consider that your body is not going to be static over the next several years. So you might also simply be seeing a progression in just needing more exogenous insulin.


That has been my experience. To adjust for seasons I need to increase my basal in fall and reduce again in spring. My gut feel is it’s a combination of differing activity levels and diet that occurs with reduced daylight hours. I also have noticed that even small weight gain of 3-4 pounds can cause a significant increase of insulin resistance.


@needlesandmath I’ve noticed a similar shift over the last few months. It may be that it’s winter and I’m more sedentary. But I’ve also been refining my ICR and other Loop settings following Kenny Fox’s advice on adjusting per some LoopnLearn YouTube video’s. Getting more stable has decreased my use of my treadmill & ellipitical because I didn’t want to inject the complexity of changes exercise threw in at the same time….need to introduce that back for mental and physical health! It’s too easy to get out of the habit at my “elder” age!


I’m the opposite and need far less insulin in the fall and winter, more in summer. Every season I need a new pump program.

I have no explanation for this reaction:
when I’m in sunlight, or the blue light from screens, my BG starts trending up within 10 minutes. If I don’t get into the shade or away from the screen, I become insulin resistant after a half hour, can’t eat or I spike like crazy. Shoot up.

I now wear this super duper 50spf sunscreen with blue light blocker all year long on any exposed skin.

I wear 50UPF clothing in spring/summer whenever possible, and hats with that extra protection.

I use the blue light filters on screens, and eyeglass lenses.

All this reduces the impact, doesn’t eliminate it, but it’s more bearable. Summers I gain weight from the extra insulin, fall I start to lose again. Without trying.


I agree @TomH it’s hard to manage several changes at once. After my run yesterday my sensitivity reset to what it was in fall, which was quite a surprise when I dosed for lunch.

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I haven’t increased my (pretty low) basal so far because my morning and overnight numbers still look the same; plus I already have to fuel up a lot for running and more basal will make that challenging. But I’m using MDI with Tresiba, not a pump, so I have less granular control over basal levels anyway.


Update on this:

I finally tried bumping up my basal from 2 to 3 units of Tresiba. This makes control a little easier but it doesn’t seem to have affected my ratios very much. Morning remains challenging and I run lower in the evenings than I necessarily want (70 after dinner, so I need a snack before bed).

While it’s still possible this is seasonal or a shift related to end-of-honeymoon, I wonder if starting a statin might have contributed. There’s fairly robust research indicating that statins can produce insulin resistance. I started mine in late Oct. and started noticing increased insulin needs in Nov. Anyone observed insulin resistance with statin use?

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Are you on statins for cholesterol?

Yep, my LDL is a little (not extremely) high. It’s well controlled w/ 10mg rosuvastatin.

I don’t have anything to offer as far as insulin resistance from statins. I don’t know anything about that.

But from your earlier post, are you high in the morning and low at night? Is that the issue with Tresiba?

If so, consider that people don’t generally have flat basal needs. It is fairly common for a person’s body to require different amounts during different parts of the day.

In your case, you could possibly reduce the Tresiba dose (which covers 24 hours), and take a very small amount of a different basal insulin at a different time of the day that would only cover a few hours.

So the 24 hours of Tresiba plus the few hours of the other type of basal insulin could match your varying basal needs much better than just a single 24 hour flat basal.

At very low doses, Levemir has a duration of about 6 hours. At very high doses, it can last almost 24 hours. So you could match your varying basal needs with the right amount of Levemir timed at the right time. :+1:

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Thanks for these thoughts. It hadn’t occurred to me to mix different time-scales of basals in this way. I may raise it with my endo as a possibility.

One reservation I have is that I’m not sure that my main problem at the moment is a basal issue at all. Raising my basal has made my evenings a little low. But it hasn’t done anything about the surges I have in the morning. I will wake up at a reasonable number (90s with 3u of Tresiba, 105-110s with 2u), but once awake I’ll go up by ~30 points. That combined with a IC ratio of around 1:4 or 1:5 makes it hard to get many carbs down in the morning. The basal changes don’t make a dent on this foot-on-the-floor problem.

And this may be a separate topic but it’s also wreaking havoc on my ability to run in the morning. I’ll start at 130-145 after having a small snack and then I spike up to 160 or 180 once I’m underway. This occurs even with a simple 3mi run at a moderate pace, and I can’t run it down–it just stays high. Getting down from that peak can take a couple of hours.

Yep, this is not a basal issue.

The fix for this is to take insulin right when you wake up. I do that.

Morning runs are difficult for this reason. It’s fine if you run a little while after you wake up, but doing it right away is tough.

2 hours is a key window. If you can wake up, take insulin and eat, and wait 2 hours, then you have fuel and not as much IOB. And the spike has somewhat diminished by then.

If you want to run as soon as you wake up, it’s a challenge with MDI. But you can take sufficient insulin to bring down your morning spike, and then fuel it with carbs during the run to prevent the inevitable drop.

Any amount of insulin can be matched with sufficient carbs. You just need to be very proactive with the carbs on impending drops.

We can get you setup with a running BG meter, like several others on FUD have now.

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Yeah, I take my insulin on waking and that keeps it somewhat in check, although I still need to move around a lot for it to kick in. It’s really struggling against the hormones and glucose dump in the AM.

I’m willing to experiment with running after eating and bolusing. Insulin tends to have a long tail for me–afternoons it can run the full 4 hours–but that’s somewhat lessened in the morning. So I might need more like 3 hours of lead time. Wouldn’t want to try it without a meter on hand.

FWIW I have the opposite problem in the afternoon/evening: I need to start fairly high (130 at least) and fuel almost immediately to keep from dropping to 70 by mile 3.


Following up on my own post to report that with the latest seasonal change my insulin needs leapt back to what they were before. That applies not just to how much mealtime insulin I need, but also to the dynamics of the insulin (e.g., speed of onset, how it responds to activity/exercise) as well as to my basal (e.g., where my bg sits before dinner). I’ve been a little more active lately but not drastically so. May just be some complex mix of temperature/sunlight/activity/hormones/mood, etc., but it’s a real qualitative change. Good to know.