Why do blood sugar levels rise after some sport?

Sometimes if insulin levels are high before you exercise, they can stay high if you're not working at a heart rate level high enough to be burning up the blood/muscle glucose that's circulating

The lactate/insulin connection is interesting: lactate is used as a substrate for energy - so it's a good thing. We tap into it generally when we're working at the threshold of aerobic (fat burning/oxygen use) and anaerobic (doesn't need oxygen to burn, so phosphate, glucose and lactate metabolism go in here).

A paper in 2002 suggested that lactate was a big insulin resistance inducer - so no getting glucose into the cell with lactate around (AJP-Endo Articles in PresS. Published on April 30, 2002 as DOI 10.1152/ajpendo.00557.2001) But more recently, work shows that lactate suppresses glycolosis (conversion of glucose into pyruvate for ATP - in short conversion of glucose into energy) not insulin uptake.

THis makes sense to me: one does lactate threshold training in endurance in order to be "glycogen sparing" - to be able to up the aerobic threshold (ability to rely on fat as fuel before cracking into the faster used up sugar supplies). Intriguingly, lactate is a by-product of anaerobic fuel burning that feeds back into the aerobic system for fuel. The better the aerobic system can utilize lactate the more effective and efficient and usually powerful it is.


So, a paper in 2008 (EFFECT OF LACTATE ON INSULIN ACTION IN RATS) also looking at rodents showed that simultaneous exposure of insulin and lactate in the rats resulted in way more glucose uptake (which would suggest improved insulin sensitivity). That's a good thing.

Related - a recent paper (http://www.ncbi.nlm.nih.gov/pmc/article ... ool=pubmed) shows that working at lactate thresholod can be a good way to improve insulin senstivity. BUT also low instensity aerobic work reduced IGF (insulin like growth factor 1) and increased circulating IGFbp (igf binding proteins).

SO - bottom line seems to be that, if muscles are working hard enough to say i'm running out of fuel; stick more glucose into me please, then glucose levels go up but genearlly speaking that elevation is going to come down after the demand has been satisfied unless the levels were a bit oversaturated to begin with.

Lactate is a good thing that should not interfere with insulin but may reduce the need for glycolosis - thus that extra load may be floating around in the blood stream. And of course if you had any kind of recovery drink during or after the bout that will add too.

Does that help? clear as mud?

mc

Hi - I have some questions / observations round this too... what you're saying about the aerobic/anaerobic threshold is really interesting, but though I have experienced recent highs after intense exercise, my blood sugar drops very dramatically during the actual duration of the exercise.

So far I've been letting my BG run a little high, about 10, before starting, as it will predictably drop by about 5 during the course of the exercise, and I'm not a huge fan of eating or drinking during exercise (i find it makes me feel quite sick).

After exercise, where I'd expect BG to fall an hour or so later, it rises - so I'm guessing that the body is trying to restore it's own glucose levels.

I would never have dreamed to inject after exercise, but would that be the solution? And will the threshold of the kind of exercise I'm doing change as I get fitter?

Any tips would be helpful - I dislike having to let bloods run high to deal with the fall, and then find they climb again afterwards - seems counter-intuitive.

Thanks, Anna

Hi all.
I have found if just wandering about shopping and browsing my bloods come down.[steady even paced activity]
If attend my excercise class they always 'rise' , so raised this up as a question to my DSN.
Was told because of the cardiovascular burn more intense activity WILL raise the blood sugar levels.
I was advised to test half hour after class, if levels are STILL high, sit rest eat couple of crackers, drink water, test again if levels have dropped too low [ I can go high with the excersise then down low ] do half of my insulin dose [basal]
When things settle a bit , eat my evening meal and then do my other half insulin dose [basal]
I have done exactly this and it DOES work for me...
We are all different and this is what I have found works for myself.
Anna.

I assume you've seen the information on the runsweet site.
http://www.runsweet.com/
Personally I never need to take any more insulin either before or after exercise, the opposite in fact... I'm always trying to minimse it. All my exercise though is aerobic.
I've been reading Kris Freemans blog. He is an olympic cross country skier and 50% is anaerobic and of course during a competitive event stress hormones play a big part. He raises his insulin by a huge amount during events.
http://blogs.fasterskier.com/krisfreema ... lance-act/
Sadly though he got it all wrong at the Olympics and I think his glucose levels fell too far... it's not an exact science even at that level

For aerobic exercise (<85% ish of your max heart rate) your muscles are mostly burning fat (almost completely at low intensity, with an increasing amount of glycogen as the intensity increases).

For anaerobic exercise (>85% ish of your max heart rate) your muscles only burn glycogen.

Once your glycogen levels become depleted (by either type of exercise) you become exhausted and stop. Your muscle glycogen depletes very quickly during aerobic exercise, and most people cannot exercise at that intensity for more than about 20-30mins.

The BG rise you are talking about is a result of your liver dumping glucose to refuel your muscle glycogen.

Even on a ketogenic diet I get huge liver dumps if I exercise aerobically (5k races @93% max HR). I ran 7.5 miles last night aerobically and my BG went down.

The Runsweet link that Phoenix posted is an excellent site for those interested in sports and injecting insulin :thumbup:

I go to the gym in the morning where I do 45 mins of weights and a 15 min run. I need to take insulin for that otherwise my sugar levels rise. If I go for a 45 min run I need sugar. When I go to rugby training I need sugar, but when I play a game I dont need sugar or insulin.

I'm putting the morning sugar levels rise down to the dawn phenomena. The rugby game down to the fact that it is quite stressful on my body so my liver produces glycogen. I'd say just pay attention to your sugar levels and act accordingly. My insulin/sugar requirements for all activities have changed over time.

I exercise a lot (3-4 times per week at the gym for 1-2hrs at a time). I have found mixed results, one of the key things which plays a role in sugar levels is the hormones. When cortisol is released depending on how you react to it, it can either lower or increase the sugar levels, then when Growth Hormone is produced that will decrease your insulin sensitivity. For us chaps upon testosterone being released it will not only burn our levels faster but will increase insulin sensitivity as well. Best thing to do is to check your sugars on a few occasions and see how you react to things. Then you can adapt, I for instance have a sweet drink during exercise to keep the sugars from dropping too much.

From my experience with my son's Type 1, his levels usually go up after sports.
My aim is that he should be 8-10 read'g before he exercises.
I make sure he has enough insulin before sport but not overdo it as there is a hypo danger. My diabetes expert book says you need less insulin before sport, as it can make a hypo more likely.

Its a case of trying to get the right balance !! Very difficult !

However, the activity is vital as it makes the insulin work better.

Thanks,
LoisP

I find that one of the key things that determine how I cope with exercise is whether my BG levels are rising or falling beforehand. I always use jelly babies to keep my sugar levels up during running and, unless there's a specific reason (such as having excess sugar beforehand to increase my BG levels to be able to run!), my BG levels always fall and I need to eat afterwards to prevent them falling further. I used to (on doc's advise) keep my BG level high (8-10) but have stopped doing this as I was ending up having readings of 12-14 before exercise. The exercise brings it down nicely but I was worried about the effects it was having in the interim. I am now comfortable going for a run when my bloods are over 5 and I adjust the number of jelly babies to suit. Intense exercise, especially interval training, needs extra sugar.

However, I have a question. I tend to find that if I am running a 10K and I take a jelly baby every mile, then when I get to mile 5 I normally end up spitting it back out. I can't explain why but it's almost as if my body is telling me I don't need it. I am not sure if this could be the result of counter regulatory hormones. Anyone else experienced this?

borofergie said:

For aerobic exercise (<85% ish of your max heart rate) your muscles are mostly burning fat (almost completely at low intensity, with an increasing amount of glycogen as the intensity increases).

For anaerobic exercise (>85% ish of your max heart rate) your muscles only burn glycogen.

Once your glycogen levels become depleted (by either type of exercise) you become exhausted and stop. Your muscle glycogen depletes very quickly during aerobic exercise, and most people cannot exercise at that intensity for more than about 20-30mins.

The BG rise you are talking about is a result of your liver dumping glucose to refuel your muscle glycogen.

Even on a ketogenic diet I get huge liver dumps if I exercise aerobically (5k races @93% max HR). I ran 7.5 miles last night aerobically and my BG went down.

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I am experiencing the same thing! Great post and thanks a lot! I will do low intensity [aerobic] workouts and report back after few weeks.

SamJB said:

I go to the gym in the morning where I do 45 mins of weights and a 15 min run. I need to take insulin for that otherwise my sugar levels rise. If I go for a 45 min run I need sugar. When I go to rugby training I need sugar, but when I play a game I dont need sugar or insulin.

I'm putting the morning sugar levels rise down to the dawn phenomena. The rugby game down to the fact that it is quite stressful on my body so my liver produces glycogen. I'd say just pay attention to your sugar levels and act accordingly. My insulin/sugar requirements for all activities have changed over time.

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Great post, speaking from experience! thanks for the types of exercises and different requirements like sugar and insulin

This is a really useful thread. I'd love some feedback too:
Today my fasting bs was 6.1. I drank water and headed for a run- 50 mins. I didn't take insulin as I can't eat before a run- it makes me feel sick and I didn't wAnt to risk a hypo. After my bs was 10.9. I have now eaten and taken 2u. I'm just wandering if I should take a small dose of insulin before my run- seems weird without eating? Any suggestions? Ta x

Lots of useful info on this thread!
Firstly, it might help to take a look at this movie:

To reply to your question @Zanshin, the high BGs you experience after a bout of high intensity exercise will be down to your body's hormonal response to your elevated heart rate. Hormones (initially glucagon and then hormones such as adrenaline and epinephrine) trigger your liver to release glucose into your blood stream. Lactate build up is a bit of a red herring and @borofergie, (a competent exerciser on low carb) is right when he states that the body utilises different fuel sources depending on the intensity. (See attached graph below)


The issue with taking insulin before you exercise is that if you risk a rapid fall in BGs - particularly if you don't actually raise your heart rate high enough to trigger your liver to release glucose.
A safer option is to firstly at the end of an intensive bout of exercise, have a 'cool-down' period where you do something aerobic and less strenuous for a further 20 - 30 mins. What this will do is allow your heart rate to fall and put an end to your body's stress response (and stop signalling the message to release glucose) The liver doesn't 'switch' off producing glucose for quite a while after a bout of exercise, so by doing a bit of less strenuous aerobic exercise, you can help your body 'mop up' the extra glucose the liver is producing.

A second option is to take some insulin after you finish your exercise. This will encourage the now depleted muscle cells to re-stock with glucose (stored as glycogen). Something to bear in mind however is that your exercise has created an energy 'deficit' in your body. What I mean by that is that your exercise has not only resulted in burning inter-muscular glycogen stores, but it has also caused your liver to release a load of its own stores of fuel. Consequently, unless you replace this with food (where appropriate with a reduced bolus) you risk your blood glucose levels falling low later on after your exercise session.

A third option (and one which is my own personal opinion based on observation, not on scientific study) may work for some and not for others, and is probably reliant on any beta cell function you have left (insulin producing function). In a healthy pancreas insulin and glucagon have opposing effects - insulin is secreted when food is on the way, or to lower BGs, and glucagon (produced by alpha cells) is secreted when there is a need to raise BGs. It is commonly recognised, that most people with T1D retain a very small amount of beta cell function. Consequently, if you eat something (no need for it to contain carbs) after you exercise, it could be enough to trigger the pancreas to secrete enough insulin to override or suppress the glucagon response, and hence moderate the liver's release of glucose.

For more info go to : www.teambloodglucose.com or join the TeamBG or Sporty Diabetic FB pages.
TeamBG will be doing parkrun Harrow on 01 August, and have other events planned too. It's an opportunity to get together with others with T1D or T2D to share strategies to maintain healthy BGs with exercise (well, that and have a bit of a laugh!). Why not join in?!

All very interesting. As I have posted in a different thread, my main problem is the immediate rise in the blood sugar levels prior to a fairly energetic game of five a side. Considering this is with a like minded group of 35 to 53 year olds (my age) all in decent shape, it will give you an idea of the pace of the game, that lasts one hour. I have been dogged with the problem all my adult playing life - we will say the past 25 non-competitive years. My insulin dose is low - 15 lantus per day, 5 novo rapid per day plus eltroxin for the thyroid. I must admit to getting a little lost on the technical stuff that featured in some of the earlier posts. Am particularly interested in the notion of taking an extra dose of novo prior to staring games. Bear in mind the games take place at 7.30 in the evenings. As the sugars rise - and they were between 14 and 16 last week during the game- though pretty good all day - between 4 and 10, I was literally unable to function properly. It is frustrating, when I see other guys my age playing comfortably and it is not from lack of effort on my behalf. Adrenalin also plays a part. This occurs as I look forward to each session. Great to get out and to clear the head.
Should I take a bolus of one unit/ one and a half before game starts. Is it more effective to take it five minutes before or half an hour before? I understand well that each individual is different. Does anyone think that it is worth a try. And of course the levels invariable drop during the period after the exercise. Often at ten o'clock the next morning. The carbs are always close by. Appreciate the advice from anyone who may have experienced this conundrum with the old diabetes control.

Colquig said:

All very interesting. As I have posted in a different thread, my main problem is the immediate rise in the blood sugar levels prior to a fairly energetic game of five a side. Considering this is with a like minded group of 35 to 53 year olds (my age) all in decent shape, it will give you an idea of the pace of the game, that lasts one hour. I have been dogged with the problem all my adult playing life - we will say the past 25 non-competitive years. My insulin dose is low - 15 lantus per day, 5 novo rapid per day plus eltroxin for the thyroid. I must admit to getting a little lost on the technical stuff that featured in some of the earlier posts. Am particularly interested in the notion of taking an extra dose of novo prior to staring games. Bear in mind the games take place at 7.30 in the evenings. As the sugars rise - and they were between 14 and 16 last week during the game- though pretty good all day - between 4 and 10, I was literally unable to function properly. It is frustrating, when I see other guys my age playing comfortably and it is not from lack of effort on my behalf. Adrenalin also plays a part. This occurs as I look forward to each session. Great to get out and to clear the head.
Should I take a bolus of one unit/ one and a half before game starts. Is it more effective to take it five minutes before or half an hour before? I understand well that each individual is different. Does anyone think that it is worth a try. And of course the levels invariable drop during the period after the exercise. Often at ten o'clock the next morning. The carbs are always close by. Appreciate the advice from anyone who may have experienced this conundrum with the old diabetes control.

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@Colquig if you know that your reaction to every match is to climb, then I think a bolus for the exercise rise is probably worth a try. As you are on a TDD of only 20, you should start off super cautious with your exercise bolus - maybe 1/2 unit say 5-10 mins before you usually start rising. Then check at half time and consider whether you need another half unit. It does differ for everyone, and it is trial and error, so best to start off as cautious as possible.

Also i think it sounds like you are rising due to the adrenaline, the atmosphere of the game, the competition etc. So as soon as these stresses go, you might find your correction suddenly works much more effectively than during the game and you will drop. Do you find you stay high after a match, or do you come down ok? Would you usually correct after a match?

I'd just be careful for post game hypos / hypos overnight after the game.