Insulin sensitivity variance

Hi all,

I offer hear that exercise can increase insulin sensitivity and that we should inject slightly less after exercising (for the remainder of the day).

My question is: “How much variance in insulin sensitivity do you see between periods of exercise and periods of not exercise?”

What is your IC Ratio for an active week vs an inactive week?

When I’m at home I sometimes exercise 2-3 times in a week (fairly intensely, often running) and my IC Ratio is perhaps 1 unit of insulin per 11g carbohydrates and my Correction Factor is perhaps 50 mg/dL per 1 unit of insulin.

I’ve spent the last two weeks traveling (not exercising) and my IC ratio is WAY different: maybe 1:4 and CF of 20:1. This enormous swing is very hard to manage (obviously).

Exercise isn’t the only thing that has changed: other confounding factors related to business travel: more alcohol, less sleep, higher carbohydrate diet.

Do you guys see your insulin sensitivity increase by 250% like I am? This feels extreme.

(I use a pump with Novolog… maybe my basal should be increasd while traveling, I would be open to trying that).


PS: mods feeel free to move this topic to another category / tag.

@Eric, @TravelingOn

You know its interesting, because I see the opposite effect when I am traveling, though not to the same extent you mention. Like you I also have more alcohol, less sleep, and higher carb diet when traveling. But when home I have very inactive days (desk job) except for exercising three, sometimes four, times a week. My total calorie burn from these exercise sessions is 1000-1500 calories. But when I am traveling, either for business or pleasure, I am not exercising but I am active every day, walking ALL the time to investigate my new location.

So instead of requiring more insulin, I require less, and I think it is due to the big increase in calorie burn from not being stuck in the office and driving every day. I need to decrease my basal by about 25%, with similar reductions in IC and CF. I just got back from Sweden, and indeed was fighting lows the whole time I was there even though I reduced my insulin intake. Ate a couple 200g chocolate bars and a couple bags of black salted licorice in the process. I probably should have reduced basal even more, but I didn’t mind eating the Swedish chocolate and licorice :slight_smile:

p.s. I definitely need to change my basal when traveling, even though it is very static when at home and I’ll go months without changing it. So I would definitely start there and work to find the new normal basal when traveling since it should require less change to the other factors and hopefully will help stability.

1 Like

I can’t speak to the specific issue of exercise, but let me reassure you that if your BG is too high you need more insulin, and you should definitely take whatever amount your body says you need. Even if it is 2.5x more than usual.

I generally find when adjusting my insulin that basal rate is the foundation, insulin:carb comes second, and correction ratio comes third. If your BG seems to be rising all by itself, several hours away from your last meal, think basal. If you believe your basal is right, but your BG always seems to be running way high 2 to 3 hours after meals, think about adjusting the insulin:carb ratio for a bigger dose (and maybe try to pre-bolus earlier if you can). If those both seem to be working but corrections don’t, then adjust the correction ratio.

Now if your insulin requirement is changing by 2.5x from one day to the next (and it’s not a bad infusion site issue) you may need to turn all 3 knobs simultaneously, or you could just put on an elevated temp basal to help get things under control, but it’s much easier to understand what’s going on if you can make smaller adjustments, one at a time, to first fix basal, then carbs, then corrections.

Be sure to carry extra glucose with you at all times when compensating for huge changes in insulin requirements, because you can’t hope to get your BG to come down without going too far. And unless you have a trustworthy CGM, be extra cautious about not going low in your sleep.


Like you mentioned, there might be other variables, like a crappy site or being sick or lack of sleep or stress or many other things.

But over time, the numbers don’t lie. Eventuality you can feel comfortable that if you need that much more insulin when you are inactive or traveling, then you really do need that much more insulin.

See if you can rule out other things and just take what you need.

I don’t think 250% is that crazy. Sometimes I go with a 40% temp basal. And guess what the multiplicative inverse of 250% is! Yep, it’s 40%. So those numbers could easily be attributable to exercise.


i have a similar situation with non-exercise days v. exercise days. i dont know which pump you use, but i use a Medtronic and have 3 different Basal Profiles available to me. so, it is very easy to set them and switch from one need to another. i have my standard profile set for swimming days, and then i have a higher basal rate set for non-swimming days. it is so easy, and it is deff easier than trying to program a TB % for X amount of hours.

also, on exercise days, post work-out, i need a small % less insulin for bolusing and my ICR changes as well. i wish my pump had diff profiles for those as well, but unfortunately it doesnt.

we should call the company and bombard them with pleas to add this feature onto their next pumps. :blush:

1 Like

But is the difference between a swimming day and non-swimming day extremely stark?

In the past I have employed different basal rates depending on exercise, but this particular thread is more focused on the 250% (or 40% if you prefer the inverse) for the Bolus rate depending on the exercise. It’s such a Huge difference I’m having trouble wrapping my head around managing it.

Take something simple like a banana: am I injecting 2 or 5 for that? That’s a huge swing and almost single handedly accounts for both hypo and hyperglycemic episodes. I don’t mind injecting more, but the variability is shocking.


I can’t speak for the others, but when I’m going to exercise rigorously for an extended time I cut my basal rate anywhere from 20 to 50% an hour before and up to an hour after. I then use a modified insulin to carb ratio that’s lower than normal to avoid any hypo / hyperglycemic events

i turn my pump off completely 2.5 hours BEFORE exercise, and then keep it off for another 2 hours during exercise. i have no IOB at all. then, on top of that, i have my basal rate lowered for swim days by 5% .

i use MUCH less insulin on swim days, especially if they run consecutively one day after the other. (usually i swim Mon, Tues, then take off Wed, then swim Thur and Friday. i dont swim sat or sunday) I dont have my ICR down pat yet, but i know without a doubt that they are quite different.

and, whats more, is that i know i am still modifying it, b/c i need much LESS insulin post swim if i do a relatively hard workout.

you are not alone !!! :blush:

@daisymae it just goes to show that while we have similarities, whe also have differences that make each of us unique. :grinning: Swimming like ballet does tend to use a greater proportion muscles and might explain the higher insulin absorption. When I swim (actually more like a sea lion floating or a toddler in water wings…) my sugar can drop by 100 points in less than 15 minutes. Running a delivery route with 180 stops never hits me that hard.

1 Like

How extreme are the exercise days, and are you doing them with low carb amounts?

Well, I guess I tend to run on the border between aerobic and anaerobic. For a while I was doing a controlled experiment where I ran exactly 7 miles at a 9:00 min/mile pace (which I would describe as low/moderate intensity for me - I could keep up that pace for 13 miles without much trouble).

Other days I find myself without much time to exercise so I’ll run about 3.5 miles up a mountain as quickly as I can - which is definitely high intensity.

Generally on running days I eat very few carbs before running, and often very little during running, and then I’ll eat something during recovery.

Im not really sure but I think I eat about 80 - 120 grams of carbs per day, exercise or not. That’s a low confidence guess.

we definitely have an increase of that much for sick days versus non sick days. Low insulin days the TDD is about 5 to 6 units – high insulin days may be 14…so there’s definitely that range.I think it’s always surprising to me just how much insulin needs may vary day to day. But I guess it shouldn’t given that people with T2 may be producing/using orders of magnitude more insulin than a person without it. Clearly, for the short-term, people’s bodies can operate within a wide range of insulin levels (with a floor obviously)

1 Like

If you are exercising regularly, I wouldn’t expect a huge change if you skipped one day. But for periods of no exercise of a week or so, this doesn’t seem too unexpected.

Not only does exercise increase your carb requirements and insulin sensitivity, but it also increases the the level of GLUT4 expression. After a week of no exercise, this can change dramatically.

what is a GLUT4 ? please forgive my ignorance. :wink:

1 Like

This post explains it: