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Exercise and BG

Discussion in 'Type 1 Diabetes' started by thetallerpaul, Apr 18, 2012.

  1. thetallerpaul

    thetallerpaul · Well-Known Member

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    Hello all,

    I've just recently started on exercise again now i'm on Insulin and can actually eat enough to feel like I have the energy for it. My question is what impact should I expect exercise to have on BG. I want to adjust my quick acting insulin based on the exercise I planned to do as on day one I got down to 4 mmol a couple of times that I wasn't expecting and had to eat as needed to drive and stuff. Not a major problem but just like to plan so I don't waste carbs eating something less nice to get sugars up when I could have had a nice cookie!

    Thanks

    Paul
     
  2. neilshots

    neilshots · Member

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    This one confuses me sometimes and i still find it hard to get it right sometimes. But if I know I am going to do exercise after a meal which is when i do most of mine, if it is likely to take around 30 mins or more, I tend to reduce my quick acting insulin by one unit prior to my meal.

    I also go by your way of thinking on the way to get your bg up again if it does go too low after a bit of exercise, why not have a cookie!! You might deserve it.
     
  3. AMBrennan

    AMBrennan · Well-Known Member

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    This will really depend on the type of exercise you're doing, and will largely be trial-and-error, I'm afraid.

    Unless you're overweight or trying to lose weight, there's no real need to reduce insulin for exercise - you can just have a cookie before starting.
     
  4. noblehead

    noblehead Type 1 · Guru
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    Paul,

    The following site has some excellent information with regards to exercising with type 1 diabetes:

    http://www.runsweet.com/
     
  5. phoenix

    phoenix Type 1 · Expert

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    Have a look at runsweet.
    Lots of good info there
    It is a matter of testing before during and after and knowing what your body does.
    I personally try not to exercise during the 2 hours after a meal because I can drop like a stone during the first 20 min; extra insulin sloshing around doesn't help. If I'm going to run during this period I would reduce the bolus for the meal. (and as I'm on a pump I'll reduce that as well). I tend to drip feed dextrose tablets during a run. Even so I'm always lowish at the end of a run because I don't take enough to raise the level very high. It doesn't bother me because I'm not going to drive afterwards.
    It's often suggested that you take in some carbs/protein after exercise in any case. It's supposed to refill glycogen stores, mend muscle etc.
     
  6. thetallerpaul

    thetallerpaul · Well-Known Member

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    Thanks all,

    I'll have a look at the runsweet stuff and see how I get on. I'm trying High Intensity lower duration work at the minute and seems to be working as long as I do it before a meal. Anything that means I can eat more food I will take!

    Paul
     
  7. Cheryl

    Cheryl · Well-Known Member

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    Also look at Diabetes.com a US website with a very good section on exercise, carb replacement & insulin reduction. It's in the diabetes management section of the website, they call it ExCarbs. This has helped me work out how much carb I use during exercise & taking into account insulin on board, starting BG, exercise duration it helps me calculate how much to reduce my insulin dose prior to exercise & how much carb I also need before/during exercise.

    I find that I cannot exercise on insulin reduction alone, I always need additional carbs.

    You need to know, or work out, how much effect 1u of insulin has on your BG & how much effect 10g carb has (if you know one, the website tells you how to work out the other). For example, I swim for 45 mins, my body needs about 40g carb for the swim. 1u drops my BG by around 2.5-3mmol depending on the time of day & I take around 1u for 10-11g carb. So if I start with a BG of 8, I can afford to drop 3mmol the equivalent of 10g carb, I then take 20g of carb before I swim & another 10 half way through, all of which adds up to the 40g (30g in actual carb & 10g which is already swilling around in my system).

    I usually swim before dinner, so don't reduce my insulin dose as it would leave me high all afternoon.

    However, if I exercise weekend mornings (cross training) I also calculate how much insulin to drop off my breakfast dise, probably 2 units, which means that I need 20g less carb during exercise to prevent the crash.

    It does take a bit of getting your head around it as there's so many variables. You just need to learn how your body reacts to exercise & have fast acting carbs on hand just in case you crash.

    Remember, that you will probably need to reduce insulin after exercise for up to 48 hours, depending upon how intense the session was, I am on a pump & run a basal rate of 80% normal from 4 hours after exercise until 24 hours afterwards to prevent hypos. Speak to your HCP about whether you should reduce basal, bolus or both, as it may be different for MDI.
     
  8. Cheryl

    Cheryl · Well-Known Member

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  9. thetallerpaul

    thetallerpaul · Well-Known Member

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    Cheryl,

    Thanks for that. The longer term impact makes a lot of sense as I had very low levels for a couple of days after a really hard days work building a garden at a school and thought it was because I was exercising for those days but since then, despite continuing to do a bit of exercise I've not seen the same lows.

    Looks like a may need to build in some more intense training days not just regular lighter exercise after all. The huge Ciabatta roll and crisps and cookie I had that day was worth the pain!

    Paul
     
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