How exercise increases the effect of insulin and carb usage

When my trainer asked me why I couldn’t exercise daily for about an hour, I did reply that it would be easier for me to find 10 minutes here and there and maybe it would add up to a total of about 45 minutes daily; I can try to find 20 minutes daily, regularly. I do understand that 3 to 10 minutes may not be considered sufficiently aerobic, get the heart rate up…etc. However, something is better than nothing. I also did not want the exercise to become a chore that I “had to do”, but rather something that I would look forward to doing. It’s about motivation. When exercise was something that was presented to me as “Why don’t you exercise to bring down or manage your BG” instead of “Exercise is generally good for you, both physically and mentally, whether you are diabetic or not.” my reactions were quite different. It’s probably similar to those who complain about not being able to eat xyz now that they’ve been diagnosed with diabetes. I don’t miss many of the diabetic unfriendly foods because they are not terribly healthy for us regardless of whether we have diabetes or not.

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Your response was very nice. How sweet to try to find something supportive out of 3-10 minutes of exercise, which really would be minimal… I miscommunicated. I absolutely LOVE my exercise, and I would probably exercise myself to death if it were available. Exercise brings me happiness, brings me serenity, and it allows me and my family to co-exist under the same roof in peace. :smiley: I am very lucky to enjoy movement the way I do as I understand a lot of people do see it as a task. That would make doing it very hard. In my case, because I enjoy it as much as I do, I use short bursts throughout the day to help out my insulin. I find as little as 2-3 minutes of jumping on the rebounder can be helpful. Sometimes I need 10. Sometimes I need the full thing. I’ve always relied heavily on exercise as part of my diabetes management, but, ironically, I was using it irresponsibly and probably doing as much damage as I was good. I ran up my blood sugar so that I could get through a workout without crashing… Or I’d correct with double the calories I burned during the workout. Anyway I’ve really cleaned up my act, and exercise has truly become a tool for better management… AND for maintaining the lowest level of sanity. :smiley:


Thought of a something I had read that maybe you’d have something to say about…

I read that a 10 second sprint at the end of a run could be enough to decrease the effects of post-exercise hypoglycemia. I’ve tried this and would be willing to do it again if there’s really anything to it, but a 41 year old woman sprinting down the street seems to alarm people every single time. So without any justification, I’d be happy to cut it out immediately. Do you have any thoughts?

I know the study to which you are referring. And I think the simplicity that they have given it is extremely overstated.

The concept is that increased physical demand triggers a release of cortisol, which would cause the liver to release glycogen and reduce the hypo.

Sure, if you are being chased by a bear in the woods, your body would fuel the activity. It would dump liver glycogen, and the glucose could be used by your muscles.

But a 10 second sprint?

Sure, a 10 second sprint might cause some people’s body to trigger a hormonal response like that. But certainly not for everyone! For some people, a 10 second sprint is only a warm-up. It means nothing, and their body might not respond at all.

This is a big over-simplification. A 10 second sprint might mean absolutely nothing to some people.

It might work if you are sufficiently stressing your body. But I think it could take much more than that. I need several miles at lactate threshold pace, or several repeats of sufficient length and insufficient rest to see that type of response.

If you are working out regularly, I suspect it would not be enough. I think there are better and more reliable ways of reducing post-workout hypos.

Are you struggling with lows after?


Thank you for the thoughtful response. You know, I’m getting a better handle on the lows following a workout, but I’m always looking for ideas. I also had my suspicions that 10 seconds of anything would be enough to alter the hours-long path I tend to get on, but far be it from me to jump to quick conclusions. Sometimes. :grin: I have tried on a couple of runs to do some sprints to see if there’s a difference, but diabetes won’t be pinned down so easily… certainly not in a couple of runs. It would take some more organization to see if there’s anything to it.

If anything, I’d say I never really know what to expect after exercise. If I knew I would crash every time, I’d have an easier time coming up with a plan. Since you asked, I assume you have a system?? Do you have any suggestions for handling blood sugar prior to, during, or post exercise?? I’m doing a lot of tests and slowly figuring out some things that work, but I always love to hear others’ ideas.

It depends on what you are doing, and what energy system you are using. Eventually you can figure out what will happen for you. It will depend on many things - workout duration and intensity, carb intake, IOB.

There is never a single answer that works for everyone. It is very personal. We can work through some things if you want. Insulin dosing and basal adjustment formulas are unique for each of us. Pre-fab solutions do not work well.

If you want to open this can of worms, here is what I would ask:

  • What type of exercise are you doing?
  • How many times per week are you exercising?
  • What is the workout intensity? Is your heart pounding or only slightly elevated?
  • How long are your workouts?
  • What is your current fitness level?
  • What is your current type of diet, in terms of carb intake? Low, medium, or high? Just ballpark your average carbs in a day .
  • I am sure you have mentioned this before, but just to get all the stuff together on a thread - do you use a pump or MDI?
  • What time of day are you exercising?
  • How soon after a meal do you exercise?

Just answering those questions is a workout by itself!


Before any of that, have you read through some of the sports wiki’s?




Exhausting, isn’t it?


I read about a related tip for dealing with a developing hypo when there’s no carb available. It said that 6 wind sprints would cause enough stress to give a brief rise in BG. The idea was that from a standing start you run at maximum acceleration and speed for 10 seconds, then stop, turn around, wait 20 seconds and go back the same way. After 6 lengths ; 3 laps you get the BG pop. As Eric indicated, YDMV.

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That’s a pretty cool trick. I hope to never ever ever have a serious reason to try it out because what a bummer if it didn’t actually work, but a cool trick anyway. :smiley:

  1. Already, we have a problem. I run, I jump (on a rebounder), and I dance. They are three very different kinds of workouts, but if I don’t rotate I get stuck with some heavy duty pain.
  2. I do a full workout about 6 times a week but mix in short ones sometimes an additional 2-3 times a day.
  3. Heart pounding is usually the intensity… at least for the heart of the workout
  4. Duration varies according to activity, but I consistently do a 40-60 minute workout
  5. Above average fitness level
  6. Carbs, like Thanos, have been sent to this earth to destroy me. Try as I might to eliminate them, they prevail. Medium consumption… (Is that even a real comparison? To Thanos? Or was that butchery?)
  7. Currently using the 670G in manual mode only. I’d go with auto mode if I thought it weren’t trying to kill me.
  8. I TRY to exercise in the morning, but i’m a mother of three boys… so i’m flexible.
  9. I’ve learned how to ride the wave… if my numbers look right directly following a meal, i try to go with it. Ideally though, I’d like to wait at least an hour before starting anything after a meal.

Of course it is. Everything about diabetes is. :slight_smile:

No pressure to try to solve anything for me… I’m just always looking for ideas. I really appreciate your taking the time with me. I’ll check out the articles this evening!

Different types of exercise will require different adjustments. But that isn’t a big deal. Most people who run do different types of runs. And it isn’t only the type of workout, but also how tired or rested you are when you do it. As long as you know ahead of time what you are doing, it is pretty easy. The surprise workouts are the tough ones.

Good. Consistent exercise makes basal much more predictable.

A heart pounding workout for that length of time moves you into much more muscle glycogen and blood glucose usage, and not as much dependency on fat metabolism. This will have a tendency to drop you both during and after.

This makes it much easier.

Carbs are not the enemy. They are the most readily usable fuel source your body has. I don’t think you should eliminate them. I think you should refill with carbs after your workouts to restock the fuel supply.

If you are working out 40-60 minutes a day x 6 times a week at moderate to high intensity, you absolutely need carbs to fuel that.

Muscle glycogen is the body’s first choice to fuel hard efforts. And the most efficient way to replace that is with carbs.

Yeah, if I had applied my brain a bit I would have remembered that. You posted the 670G videos and have posted about it. Duh. I remember that now

Pumps make it easier. But manual mode is the way to go. Auto mode will never do for exercise what you can do manually.

A few things to think about. So you have breakfast before? Working out an hour after eating is tough, because you have more IOB and the food is still metabolizing. If you can wait a bit longer this can help.

Ideally, you want to exercise with sufficient muscle glycogen stores (meaning you have been eating enough carbs to replenish what you use), and with minimal IOB.

Are any of these workouts spiking you? You can check your heart rate to determine which is a spike type of workout, and which workouts will drop you. Once you know the intensity of the workouts as it relates to your heart rate, and what heart rate you see a spike, you can start to make adjustments of whether you want to lower basal or add insulin.

Which is most difficult one you have as far as BG? Let’s start with that one.

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Correction: auto mode will never do for ANYTHING what you can do manually…

Back to reading…

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Makes perfect sense… I always drop. The only time I’ve ever gone higher is when I started way too high than was safe.[quote=“Eric, post:29, topic:3857”]
I don’t think you should eliminate them.

I could hug you. I really like my carbs but have fought hard to cut them out. Ironically, the harder I fight, the more I eat. :roll_eyes: But I am active from sun up till sun down, so I’m burning energy all day.

I aim for that— forgettable— so success! :grin:

And I wasn’t done, but the doctor’s in so to be continued…

Hi again, Eric! I have a friend who struggles BIG time with her blood sugar during exercise… She says she almost always has to stop early because of crashes. I gave her your questions and have brought back her answers for your review… Do you have any ideas for how she could be handling things? I

Here are her answers:

What type of exercise are you doing?
I am doing about 30 mins of weights - 3 sets of 15 reps on 5-6 machines - and 30 mins of cardio medium intensity
How many times per week are you exercising? as many as I can, usually 3-5 times per week.
What is the workout intensity? Is your heart pounding or only slightly elevated? My heart rate is slightly elevated so I’m burning BG not making my body dump sugar to increase it. And if I do higher intensity level, then I can also plummet with not warning.
How long are your workouts? approx. an hour unless I can only do cardio, then 30 mins.
What is your current fitness level? I would consider it active to very active - I’m more of an endurance person, not interval type.
What is your current type of diet, in terms of carb intake? Low, medium, or high? Just ballpark your average carbs in a day .
Ballpark carb average is 120-130 per day. I tend to eat everything in moderation and try to have a fruit, protein, starch in a meal. My fruit portions tend to be small - a clementine, not a huge naval orange.
I am sure you have mentioned this before, but just to get all the stuff together on a thread - do you use a pump or MDI?
I’m using a pump in MM
What time of day are you exercising? During the week, I exercise when I get home from work, about 6pm-7pm, before dinner. It is usually is the time of day that I am guaranteed NOT to have insulin on board from lunch. On the weekend, the gym doesn’t stay open after 6pm, so I have to either work out first thing in the morning, which is a hit-or-miss on how it will affect my blood sugar or late morning before lunch. On the weekends, I tend to skip the gym and go for a 3-4mile walk with my husband…who also works out with me during the week.
How soon after a meal do you exercise? It’s usually 4-5hrs at least after a meal.
Additional info: During the week, if my BG is in a decent range - around 150 - I will start a temp basal of 50% when I get in the car for my 30 minute commute at 5pm. My husband and I get to the gym about 6-615pm. Work out for an hour, doing weights first then cardio. If my BG is going low, I suspend the pump so I don’t get too bad of a low. If BG is stable, then I end temp basal/restart pump about 10 mins before the end of cardio. Then we go home and eat dinner within an hour.
Whew!!! Does that answer them all and then some!!!

(Thank you, Eric!!

I read through it all. Sounds like she is doing it correctly with no IOB, but is she crashing mostly during the cardio stuff?

The medium intensity stuff will be the area that causes the biggest BG drop (much more than low intensity. And very high intensity will cause a spike rather than a drop).

Glycolysis is the process where the body takes glucose and breaks it into pyruvate. One molecule of glucose, a 6 carbon molecule, is broken into two molecules of pyruvate, a 3 carbon molecule). (Other things are involved in the equation, but don’t want to get into the weeds here).

Glycolysis takes place in the cytosol of the cells, in the free space inside of the cell membrane. Cells take up glucose from the blood, and then glycolysis can occur right away if there is an immediate need for energy.

So what happens on the medium intensity workouts is an immediate need for energy which is pulling glucose from the blood. It is a different energy system than if you are doing low intensity and using more fat metabolism.

The way to counter this is to either a) provide more glucose in the blood at the point when it starts, or b) reduce the insulin (even more than the 50% basal cut-down), or c) a combination of those, which is probably best.

You can also consider the contraction mediated pathway which I posted about at the top of this thread. Exercise of sufficient intensity will greatly reduce the need for insulin to allow glucose to be used.

Anyway, a lot of blah-blah here. But the simple suggestion is to reduce that basal (turn it off completely close to the start of the cardio), and take a bit of carbs to provide glucose for the body to take from the blood.


Diabetes is not always consistent. We could eat, behave the same way and won’t necessarily have the same BG. However, by being consistent, it does reduce one parameter. I’ve noticed that the more consistent I am in what I eat, or how much and the type of exercise, the more “predictable” my BG is.

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I am sooooooo up to my ears in things to do and hope you didn’t think I was being rude by not responding. I just passed your information along to my friend, and I plan on giving it another look to see how it lines up with my own scenario. I really do appreciate your taking the time to respond!

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So out of your entire thoroughly presented and detailed response, she came up with this:

“but at what BG level should I suspend insulin delivery versus keeping the low temp basal rate going?”

The next thing i’ll do is just bring her over here so you can have a real live conversation…

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There really are no hard-and-fast numbers for anything we do, ya know?

No perfect formulas that work exactly the same every time. Just general figures to which you make adjustments depending on the circumstances.

I have mentioned before that no two 85 BG’s are the same. A flat 85, a slowly rising 85, a plummeting 85, an 85 with a ton of insulin on the way, an 85 with a bunch of food about to hit.

I don’t like the idea of only looking at numbers for things because it’s just part of the picture.

Ask @daisymae what I always tell her to use! :grinning:
:yoda: image


Sorry if this is obvious, I am just getting started.

For someone with type 1 but still in honeymoon and not yet taking insulin or oral agents, how would intense weight lifting affect insulin requirements? If I understand correctly it increases sensitivity so it could potentially prolong the honeymoon period? Wouldn’t an increase in muscle mass require more dietary glucose?

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I can’t answer about if it would extend the honeymoon period. I suspect it is possible, just because exercise increases your ability to utilize carbs efficiently with less insulin. But I can’t really say.

As far as muscle mass and the amount of glucose you consume, in your skeletal muscle, glycogen will be stored at approximately 1–2% of the muscle mass. So more muscle mass means you would need more carbs to be fully refueled. That is why carb recommendations for athletes are always based on weight. The more you weigh, the more you need.