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Insulin and exercise

vanarchre

Well-Known Member
Recently during my evening exercise I have found my blood sugars rising (which I know is not that uncommon). I have tried countering this by taking a little insulin before the exercise, which seems to keep me stable but I do have to be careful not to go low in the night.

My doctor seemed to think that it was crazy to take insulin before exercise. Perhaps she is right but I could not really understand her rationale (it was not a fear of hypos during the exercise). She said that it would be better to let my blood sugars go up to 13 or 14 and to come down slowly afterwards.

Can anybody explain my doctor's point of view or give some experience of how they have dealt with a situation such as this?
 
unfortunately your doctor's point of view will be of the T1 patients that do not pay any attention to close detail
( next appt ask her how many achieve their A1c target to start with )

assume your doctor is working more for a worst case scenario and a preventative approach rather than best practise.

most of us here aim for best practise and would agree that you should adapt and do what works best for you..............
 
What really confused me was that they started talking about effects on the liver from not having any glucose. When I tried to understand what exactly they meant by this they seemed inconsistent and I could not figure out if they were, to some extent, trying to bamboozle me. Does anyone know if there is a particular reason why taking insulin before high-intensity exercise is problematic?
 
@vanarchre

When your blood sugars go up from exercising im assuming you are doing intense exercise. Intense exercise - resistance training, HIIT, competition - causes adrenaline to be released. Adrenaline is counter regulatory to insulin and causes increased blood sugar. You can see this even in non diabetic sportsmen doing intense exercise, except they come back down pretty quickly & we don't!

Lots of diabetics will bolus for exercise to fight this rise. Have a look at the runsweet website.

Now, when your doctor is talking about the effects on the liver of not having any glucose ... I think she is talking about this: when you exercise your body will burn glucose in the muscles and then in the liver for energy. Your body will then want to concentrate on restocking your liver glucose stores first - this makes you vulnerable to hypos post exercise and if you hypo with an unstocked liver glucose store that is risky.

However, I don't think this is a reason not to bolus pre exercise to combat the exercise rises. Goodness knows it is going to be almost impossible to maintain intense exercise with blood sugars of 13-14! That's what the phrase running through treacle was designed for.

But, if you knock the highs on the head then lows might become a problem. So you could be cautious of this by making sure you take on carbs post exercise to help with the liver restocking. You could consider reducing and post exercise bolus and reducing post exercise basal to minimise the delayed hypos from exercise.

I suspect your doctor isn't trying to bamboozle you, it's more likely she is bamboozled herself. It is complicated. Check out run sweet for doctors who do know what they are talking about on type 1 + exercise.

http://www.runsweet.com/
 
Hi when I exercise, either by walking or diy and also gardening, I take less Insulin, so I don't hypo. But obviously it does depend on what my BS is before the meal, ie breakfast or lunch. It's a balancing act.
 
catapillar said:
@vanarchre


I suspect your doctor isn't trying to bamboozle you, it's more likely she is bamboozled herself. It is complicated. Check out run sweet for doctors who do know what they are talking about on type 1 + exercise.

http://www.runsweet.com/
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Thanks for the detail. And thanks to everyone else for the input.

When my doctor says things about just allowing myself to be 14 or so then it does make me question her more generally. I don't want to be contrary to what she says but I just want to find out what is right.

Having said that she actually mentioned the runsweet website when I last saw her and said that she very much respected the doctor and would abide by whatever he says.

I notice that for brief intense exercise it says:

'Bolus reduction not advised

May require additional conservative bolus dose correction if hyperglycaemia develops'

Which seems to be in line with what I was doing.

To me it would seem logical to take the insulin before the exercise and then to have some carbs and reduce my insulin afterwards. If this is incorrect then I'm happy to be told so though.
 
Robinredbreast said:
Hi when I exercise, either by walking or diy and also gardening, I take less Insulin, so I don't hypo. But obviously it does depend on what my BS is before the meal, ie breakfast or lunch. It's a balancing act.
Click to expand...

Lighter exercise has always dropped me slowly so I can only agree with this. I used to play golf occasionally and the hypos would sneak up if I wasn't careful.
 
I have struggled in the past when going to the gym. Not a solution that works for all but I normally go after a meal and take off two units of bolus. I am on a 1:1 ratio.
 
The reason it may be 'frowned upon' to take insulin before exercise is that it leaves you open to rapid blood glucose fall. Naturally produced insulin lasts only about four minutes within the body, and production is normally switched off very soon after any activity begins. Infused/injected insulin circulates in the body for four hours or so however. This means that your muscles are doubly primed to take glucose out of the bloodstream. Blood glucose 'transporters' in your muscles are not only activated to transport glucose out of your blood by your activity, but are doubled up in their activity by higher levels of insulin. Unless you can be sure your activity is going to induce a stress response, it is a bit of a risky strategy.

BG spikes from a stress response can sometimes (anecdotally) be moderated by eating something before the activity (even a zero carb snack). Theoretically this could work (if you have retained a small amount of insulin production). Insulin and glucagon normally play 'tag team' in the pancreas - when one is secreted, the other is suppressed. Eating something could induce a small insulin response and help counter glucagon secretion from the pancreas (which is one of the the triggers for the liver to start releasing glucose into the bloodstream).
For more info, get in touch with www.teambloodglucose.com who will be able to advise.
 

Thanks for getting back to me. I have to be honest and say that I'm a bit confused though.

You say that a non-diabetic switches off producing insulin when they exercise. My doctor said that they would still produce insulin. If they did not would they not have very high blood sugar levels after intense activity?

Actually, thinking about it, are you just saying that a non-diabetic would only produce the insulin that they need during exercise while a diabetic has the excess kicking about?

Not sure that I'm producing any insulin so I'm not sure the second paragraph applies to me.

Thanks for that link. I might try their Facebook page.
 
vanarchre said:
Actually, thinking about it, are you just saying that a non-diabetic would only produce the insulin that they need during exercise while a diabetic has the excess kicking about?
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This is the key point. What I find is that stress reaction inducing exercise needs insulin with it, but by having a protein shake post exercise, the excess protein in that gets converted to glucose anyway and solves the issues of post exercise hypos as a result of the insulin with the weight training.

What I do have to be aware of is the overnight hypos though, so find that reduced basals are necessary to avoid them. This can be down to almost zero depending on how glycogen depleting the exercise has been.
 
Hi @vanarchre - I'm in the middle of a bit of a 'trial and error' approach myself at the moment on this very question!

Until this week, and bearing in mind my exercising 'career' has so been only about 18 months long altogether - I was only exercising within an hour at most of having taken insulin and eating a meal. With the exercise planned in advance (what IS spontaneity in the life of a type 1 diabetic anyway?!) I would generally take 50% of my regular mealtime bolus of insulin, then, in the case of swimming, I would disconnect the pump and have my swim, and then I typically raise my pump's basal rate to 150% for a couple of hours afterwards (I tend, you see, to finish exercising with a blood glucose of around 5.5-6.5mmol/l, but then shoot up massively).

After a 10-week break from exercise I've just this week got back to daily swimming (and am considering - against the advice of more sensible folk around me - going back to parkrun tomorrow) - and I'm trying a different approach.

NOT having porridge before my swim! This creates the scenario of having insulin before exercise but without food. I've worked it out this way - if I'm over 6.0mmol/l thirty minutes before my swim, I will take a correction bolus of 50% (as worked out by my pump). I then go for my swim. This morning I was 6.2 afterwards, having been 7.2 beforehand (and taken insulin). Took 50% of my breakfast bolus (two boiled eggs), AND set a temporary basal rate of 150% for 90 minutes.

My Libre graph has been a straight line in the sixes and sevens between suppertime last night and 2pm this afternoon. Really, really pleased.

I'd never have 'risked' taking insulin without food in advance of exercise before I became really serious about my low-carb lifestyle - I would always have, in this order, reduced bolus insulin + porridge + exercise + increased basal insulin.

For the record - and this means I've only explored half your point, really - I have NOT yet worked out how to make it work when my blood sugar is LOWER than 6.0 when I test before exercising. Trying to experiment to find out the right amount of insulin to keep me safe (i.e. not low) and not make me high (being high is the thing I hate most in the world).

Trial and error and lots of testing is the short answer - albeit a boring one!!!

 

Hi there,
It sounds as though you have a very good understanding of what happens. That's correct that for somebody with a functioning pancreas, their insulin secretion will match the requirement. If bloods begin to rise, then insulin will be secreted. The big difference though is that the life of the insulin is very short and manages blood glucose levels back down safely.

I hope I explained the 'transporter' situation adequately, because it does impact on how efficient your muscles are at taking glucose out of your bloodstream. Glut4 transporters are the receptors within the muscles which facilitate the uptake of glucose into the cells. They are generally mobilised by insulin, however when you exercise, your contracting muscles cause the proliferation of numbers and additionally the transporters mobilise to the surface of your cells. Consequently insulin is no longer required for glucose uptake. Add insulin to the mix artificially and you are susceptible to very rapid glucose uptake (and corresponding rapid blood glucose fall).
How you choose to manage your BGs is down to you, but I if you have a fuller understanding of how your body works you'll be able to weigh up the potential 'risks' involved.

Hope I explained that ok.
 

Trial and error and lots of testing is often the answer! Thanks for sharing this experience. What you say makes sense. It is interesting to know what works for different people.
 

How does reducing the basal work for you the next day? I understand the benefit/necessity of doing it overnight but do you then have issues because you have less basal during the following day?
 


Thanks for that. Very nice to hear some of the science behind what is happening to me. I appreciate the response.
 
I
vanarchre said:
How does reducing the basal work for you the next day? I understand the benefit/necessity of doing it overnight but do you then have issues because you have less basal during the following day?
Click to expand...
What I used to do on MDI was take two shots of Levemir daily. I'd titrated it so that I took a dose at 9.30pm and a dose at 7.30am and needed to do a fast acting shot on waking to counter waking/dawn phenomenon. My daytime dose was approximately 1.75x my overnight dose. I then used to reduce just the overnight dose by around 25%, so the next day wasn't affected.

On the pump, I just run a 6 hour temporary basal at a reduced level (down about 25% again).
 

That makes sense. I think I need a pump. My diabetes team suggested moving to a twice a day basal system but I struggle to find the space on my legs as it is. Hopefully they'll put me in for one soon.
 
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