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Type 1 diabetes and energy loss during strenuous exercise

Well, It took me a while but I finally figured out why I was always so tired and energyless halfway through my 5k runs...My BG was too low!!

What I don't understand is how low BG relates to loss of energy?
For example I take in 100 carbs 4 hours before a run. I take too much insulin. As a result, halfway through my run my BG dips way down to 42 and all of a sudden my energy is zero!

My question is...what happened to the 100g of carbs that I stored as energy?  


second scenario....I take in 100 carbs 4 hours before a run. my BG shoots up to 229. I take 2 units of insulin. Prior to the run a couple hours later my bg is 136. I eat a piece of hard candy before I run 2.5 miles. My BG after the run is 60.  It seems like I perform exercise better when My BG is high like between 140-160 range starting off. The second scenario is what happened today, and i actually felt great after the run.


So what's going on here? No matter how many carbs I eat and store for energy, my energy is still sapped when my BG gets too low.  I guess I'm confused about how energy is used in the body and how it correlates with BG levels.  Can somebody please explain?  Thanks.  

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Well, Here is my guess. Type 1 diabetics are unable to metabolize carbs/sugar, so insulin helps us do that. Not only is the insulin helping you metabolize carbs but exercise causes huge drops in glucose because it causes the insulin to work harder and faster.

Lows are very exhausting, so its normal, you cant expect to have energy with a low because there isn't enough sugar running through your blood for energy, remember, we use carbs for energy and when you are low, there are NONE!

Most athletes I know keep there levels higher than normal, if you are going to run, taking insulin before a run isn't a good idea.

if you are on a pump you can adjust basals and take smaller amounts of insulin to help so you wont take two whole units and come crashing down. I've learned to never correct before a work out or at least give myself less than half the normal amount since I will be exercising.

Also, its important to lower your basal 1 hour before you began working out like if you take .600 units during those hours of work out, cut it in half. Thats what I do. it will take some time to figure it out but you'll get it down.

thank you

Hey I'm a runner too!
The way I had it explained to me by my gym trainer was that glucose is not usable to us as it is. We need insulin to unlock it, If you sugar is 200 and no insulin then it wont do any good to to you.
The issue is that exercise and esp running for me lowers insulin resistance even when I thought I had no insulin resistance. It takes less to do the same job.

I have worked out a formula. I reduce my basal by 65% for 30 min before and 2 hours after I run, and of course during.

I do not start running until my BG is around 150. If you have a CGM you can see aht your sugar will spike at first from the release of muscle sugars. Then it will start dropping.
I try to eat GU or some kind of carb gel. The gels have a little more lasting power than glucose tablets or gatoraid . I try to keep myself over 100 but not over 160.

I will bomb out if my sugars go too low OR too high.
It took me a month or so to work out my sugar intake and basal insulin.
The reality is we as diabetics can not store carbs or sugar or energy that way.
We need to parse it out as we go.

Play around with it and see if you can find a good formula.

If the insulin molecule is docking to the insulin receptor of a cell it will order the cell to let blood glucose into the inner part of the cell. Unfortunately this will happen even when the cell is not in much need of glucose. The glucose will just float around until it is needed to fuel the cell. The problem is that the cell can not give the glucose back if other cells are in greater need.

The healthy human body is micro dosing the insulin according to the blood glucose. If the BG starts to drop it will reduce the output of insulin very quickly. With very little traces of insulin the healthy body can even release glucose to prevent the BG from dropping. With these reactions it will manage to keep the blood glucose in a range from 80 to 130 all the time (with some exceptions). This healthy BG level will guarantee that the brain and other nerve cells are always sufficiently supplied with glucose. These nerve cells can take glucose out of the blood stream at any point in time because they can act independent from the insulin normal cells will need.

By being insulin dependent we inject much more insulin than is needed. We do not micro manage but take huge amounts of background insulin. There is always insulin present and because of that the liver will never release glucose to prevent lows. So this helpful mechanismn is broken for us.

With aerobic sports the muscles can burn massive amounts of glucose. With too much insulin on board the normal cells will take too much glucose from the blood stream. In combination only little glucose remains in the circulatory blood stream. This will get really troublesome if the glycagon store of the muscles is depleted (after 45 min of exercise). Now the muscles can not cover their additional needs for glucose from the blood stream. In addition the cells of the nervous system will have problem to operate because their fuel - the glucose - is missing. Of course you will get weaker and the risk of a severe low is imminent.

To really master sports you have to watch the insulin on board (the insulin that is active in your body from the last injection). It is a fine balancing act because your body will need insulin and carbs to function properly. You just need to give your body just enough insulin and carbs to prevent a low. This is really an art to do. It takes experience to be really got at that. I prefer to not raise my blood glucose before the sports. Just shortly before I will eat some very fast acting carbs like orange juice or glucose tabs. This needs to be orchestrated in a way that the digestion of the carbs can cover the needs from the activity. It will need some fine-tuning to find the right timing otherwise the digestion will be slower than the body is consuming the carbs. This will of course lead to a low. We are in charge of our blood glucose and this has its hardships no doubt about that. We are all that different in our reactions that I can only give this general advice: try it again and again with different foods and learn about the reactions of your body. You will find a way to handle exercise.

Just to make the picture complete: anaerobic exercise can cause different reactions. Here it is likely that the body will increase the blood glucose to fuel the muscles. Thus we likely need more insulin on board to counteract this reaction and to prevent a huge spike afterwards.

http://bcendocrineresearch.com/newsletter/v04/n02/Exercise_and_Bloo... might help you:

Just in reply to Holger: I have heard of 'liver dumps' where glucose does get released by the body, often as a 'fail safe' of lows, particularly in a fasting state? Do you agree with this?
Also, i understand insulin on board is a huge thing. Right now im honeymooning as a type 1 and only take 1 unit for breakfast to cover. I have tried having half a unit, have breakfast, run sugars high and exercise in 2 hours after but have found it was a terrible feeling. I find that i need the full unit to function. Now im not on a pump so im shovelling more carbs than i like to compensate for lantus in the background, but when my honeymoon is 'over' and lets say i have 2 units to cover breakfast. If i half that to 1 is it more likely i would feel terrible again during exercise and need a full 2 units on board (albeit the tail end of insulin)? Or would that perhaps be an occurance where 1 unit might provide enough energy for a good workout and maintain a higher bglucose reading to get through it. Or, again, is this very individualised. Interested in your thoughts :)

The glucose release of the liver is blocked as long as there is insulin in the blood stream. The healthy body will not release insulin if the blood glucose is going lower. The liver has not implemented a glucose detector because it just uses the presents if insulin as an indicator. Thus the "fail safe" mode of the liver is broken by design for us. This is why most researchers say that the symogi effect does not exist for insulin dependent diabetics. The symogi is often confused by the hormonally induced dawn phenomen that will increase with lower blood glucose. However this is just a hormonal reaction to provide glucose in the morning (for millions of years we had no breakfast). It might be possible that some people see a reaction of their liver with lows but it will be rare.

With theses tiny amounts it is difficult to get it right. I myself know the situation that 5 units of levemir at night might be too much but 4 units is not enough. You might feel terrible because you are actually missing insulin. Maybe you just get a fraction of the dosage you have dialed at these low dosages. Instead of reducing the dosage to 1 or 1.5 units you could just eat more. I think most very active people would prefer to fuel their body instead of restricting their needs.

But there's always some (basal) insulin floating around, unless you've really zeroed it out? I wonder if maybe there's thresholds for some of the hormonal phenomenon that, since they don't present pathologically, like diabetes, are underexplored, in terms of their impact on us? It may not be "glucose release" as much as hormones being released but I've had a few times where I'll "attack" lower than expected BG running by running some hard intervals and it seems to help boost BG a bit?

I was of the "I need to fuel" school too but, after encountering the low-carb gang here, I tried not fuelling before a big running week (maybe Jan 2011?) and had a really good week, ran well, one of my first 30+ mile weeks? I think the fuelling is necessary but not as much as in a lot of sources. One of my friends is into P90X and has gotten huge on 1700 calories/ day, although he's recently adjusted it to 2000, for a 6'0" 190 lb guy. A lot of what he seems to do is to "aim" the carbs to fuel particular aspects of development and I think a lot of his servings tend towards the 15-30G size with no apparent ill-effects on his performance?

I think the threshold is very low - likely too low for us. We all dance at the edge of being in deficit of potassium. This is also caused by the little extra insulin that is always present in us.

If my muscles start to kick the dirt they will burn carbs at very high rates. I could not exercise for 40 minutes without 20g of rapid carbs on board.

Yeah, I think it's more of a balance issue between glucose and glucagon that prevents the liver from releasing glucose into the bloodstream. A lot of diabetics here talk about suger spikes after exercising. It look like adding adrenaline to the mix of hormones can tip the balance in favor of glucose production and completely swamp out the action of insulin, resulting in high sugar spikes.

I know when I was younger, I would "bounce" a lot, have BG crashes followed by BG spikes without a correction. It could be that the intense hypo symptoms stressed me out enough to get an adrenaline release, or maybe there has been some kind of loss of glucagon response over time.

Holger and all, thanks for clearing up my misunderstandings. I finally have the light bulb moment! :)

First off, I was very misinformed to believe that insulin literally converted carbs to glucose and that cells stored glucose for "later usage." OMG was I way off!! I also literally thought that insulin converted carbs into glucose.

Now that I understand the relationship between the liver functions and glucose as you explained. Are you saying your energy pretty much comes from the glucose floating around in your bloodstream and that this whole "storing of carbs." concept is a bit exaggerated?

I decided to conduct a little experiment:
Last night at around 10p my BG was 331(on purpose). I took two units of Novolog. at 3am my BG was 245. I took 1.5 unit of insulin and ran 2.5 miles 15 minutes later. Towards the end of my run, I started to feel myself becoming weak( not out of breath but literally weak). Immediately after completing my run my BG was 109.

What I gathered from this experiment is that I probably should not have taken that 1.5 unit of insulin before my run because I dropped too fast and way too soon. For the most part, I felt pretty good during the run. But I'm starting to think that contrary to what people say about 100-130 being the ideal BG range, I tend to think that it depends on the individual and the level of activity. Quite frankly because I'm so active, I function better when my BG runs kind of high. Is that strange or unusual?

Oh, I forgot to mention that I take 10 units of Levemir once everyday at around 1pm




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