Increased blood glucose after exercise

I am a very active person. Including doing a huge amount of walking throughout the week. Plus higher intensity exercises 2 to 3 times weekly. I however haven't done any cycling since my huge 6 stone weight loss and diagnosis. I however went cycling on the weekend just before lunch. This was for 30 minutes at a very high intensity. I normally reduce my next QA by about 40% for exercise which works for me. However I done this after my cycle and then my levels were very high for the rest of the day between 14mmols to 17mmols plus till about lunchtime the next day. Can anyone shine some light on this please. I know that all my QA doses and background are correct, and my carb counting was fine. I even gave corrective doses for dinner the same day and breakfast the next and my levels still didn't come into range.

Hello,

30 minutes of high intensity exercise would be far more likely to raise your BGLs than to lower them. Aerobic cardiovascular exercise for longer than 45 minutes will usually lower them, but high intensity exercise for 30 minutes will be mostly anaerobic exercise and that has the effect of raising your BGLs.

The science behind it is extremely well covered in the book "Your Diabetes Science Experiment" by Ginger Vieira available on Amazon - ISBN 978-1481062008. I have left my copy at work, but can reread the relevant section again tomorrow and give you the basics then. Raising for 24 hours afterwards is a little unusual though, trending downwards in the 24 hours afterwards is usually the expected outcome, even for anaerobic exercise. It would be interesting to know if this is repeatable, or just a one-off. One-offs do happen, especially when you are trying something you haven't done for a while.

Cheers,
Warwick.

That's great thanks for getting back so quickly. I'm going to go for a cycle now we shall see what happens. If you could send through some info from your book that would be great.
Thanks a lot. Gari

OK, so after rereading the relevant section again, the science goes like this:

Anaerobic exercise uses a lot of energy but can't use oxygen efficiently. Your muscles need energy, but can't get it only from the blood stream as this supply gets exhausted quickly during anaerobic exercise.

Glycogen from the muscles and liver gets released to provide the required energy, but needs insulin to transfer the resulting glucose into the muscles. If you don't have enough insulin for this extra glucose, then your BGLs will rise.

As you continue to exercise anaerobically, you can experience lactic acid build up. This is a result of muscle breakdown and glycogen and glucose forming Lactic acid. The body doesn't like having the lactic acid around (hence the reason your muscles start to burn of you exercise really hard). When you stop, the lactic acid gets converted to glucose, and again if there isn't enough on-board insulin, then your BGLs will rise.

Aerobic exercise is different in that there is much less muscle break down, and the glycogen gets released at a slower rate without the lactic acid buildup. When the glycogen store is depleted (after about 45-60 minutes of aerobic exercise, the BGLs will begin to drop unless extra carb is taken in.

After exercise, the body prefers to use fat as a fuel source, but first the muscles and glycogen stores need to be replenished. If you don't take in enough carb and protein to achieve the refuelling of the glycogen stores, then the body will break down muscle (which is much more expensive than fat in terms of energy requirements) and this will cause the BGLs to rise as the muscle is broken down with a byproduct being glucose.

So the important things to note for anaerobic exercise is that you need some insulin beforehand to cover the increase in BGLs from lactic acid and glycogen production, and eat well (carbs and protein) after the exercise to replenish the glycogen stores.

Hope this helps.
Warwick.

Hi Warrick i went for a 30 minute cycle in to london and then walked round for about 30 mins then cycled back again about 30 minutes. I was hovering around 4.5 for a few hours after. I gave a 40% reduction for my dinner and had a hypo. So i suppose w
Your theory about eating extra carbs for aerobic exercise is right. What i worry about is finding the right balance of knowong when i am doing aerobic or anaerobic this could e a fine line. So the taking of QA before exercise sounds a little scary incase when i start it turns out that it will be aerobic. Any thoughts

Anaerobic exercise happens at high intensity, so if your cycling was at high intensity both ways, then that would be anaerobic, but if it is the sort of cycling that you could whistle a tune while riding, then it will be very aerobic instead.

I cycle to and from work each week day, (an hour each way, gradual uphill on the way to work, nice and downhill on the way home) and my BGLs follow the pattern of aerobic activity. It is fairly rare that I cycle with intensity - having a newborn in the house means I am too sleep-deprived to feel energetic enough :-) I never hypo on the way to work because it is within a couple of hours after breakfast and I have both carbs and QA on board, but I do have to be careful in the hours afterwards until lunchtime. Going home, I have to eat before cycling or I will with 100% certainty hypo. I could lower BI, but it tends to lead to highs at other times, so I don't.

I'd suggest that you don't take additional QA unless you see a definite pattern of highs after cycling. If you do, then you can cautiously increase your QA before cycling, but one-off rises in BGLs do happen, especially with new activities so you may not see that again.

Take care,
Warwick.

Some very interesting findings. I always thought that there was a significant difference between anaerobic and aerobic activity on my levels and this reinforces my belief. The science element coincides with my thinking too, which is encouraging. My view was built around what I had read about non-diabetics and their consumption of carbohydrates for cycling although this is for events that last over three hours and will be a mixture of efforts. I will have to see if I can get hold of a copy of the book mentioned to read further in to the subject. I am looking to improve my cycling so hopefully now armed with a bit more knowledge and resources I may yet be able to see some advancement.

Hi James,

The book is self-published by Ginger and the only place I have seen it for sale is on Amazon. It is well worth the money though. It certainly cleared a lot of my thinking about type 1 diabetes. Competitive exercise usually raises BGLs too as adrenaline produced blunts the effects of insulin.

Cheers,
Warwick.