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.