Hi
@davidponting, The following is from my experience on insulin for 51 years. It is not professional advice or opinion.
It is a generally agreed-upon fact that exercising with a
starting BSL above 14 mmol/l causes the liver to release more glucose and there is apparently a biochemical reason for this. Some may say that they can exercise successfully above this starting point, but the amount of insulin on board etc needs to be factored in. ( and the more insulin there is on board the more risk of hypos at some point). I have cycled, canoed and kayaked, run and played squash.
Initially the 3 options suggested by my doctors to adapt to exercise as a diabetic were: 1)
reduce the insulin dose of that insulin working during the exercise period and for 8 hours afterward, 2)
eat carbs before and during exercise 3)
a combination of both.
Also it was pointed out that there were about 3 ways that diabetics on insulin react initially to exercise, compared to starting BSLs of less than 14 mmol/l): A)
BSLs go up, B)
BSLs go down C),
BSLs stay near the same.
For me exercise, particularly vigorous exercise, sends my BSL up initially BUT without some adjustment in insulin, my BSLs plummet by about the 6 hour mark. Of course it depends to a degree on the intensity and duration of said exercise.
So I had to ensure that there was sufficient insulin in me to try to keep the initial BSL rise during exercise (probably adrenaline- caused) but not so much as to contribute to a low BSL at 6 hours plus.
Starting at > 14 mmol/l lead to incredible muscle ache and no lowering of BSLs later. A waste of effort !!
Eating more food tended to make me nauseous during exercise. I did not stint however on taking fluid to fend off dehydration.
I found that using
less vigorous exercise led to less initial upping of BSL. And ensuring that I calculated for only a mild reduction of short-acting insulin but a 20%+ reduction on the long-acting (Levemir - 12 to 16 hours) exercise became manageable.
I also consider that
exercise needs to have meaning. This might be aligned to a
cost-benefit analysis but involves costs such as boredom of, say I repetitive exercise, and benefits such as sociability (cycling alone vs in a club)
Now that I am on an insulin pump I lower my basal rate by 20 to 30 % for 4 to 5 hours just before setting out for an hour or two's quick walk with weights. That insulin adjustment seems to allow for an initial BSLs rise but also for a potential fall in BSL later.
I use Novorapid in the pump which has a peak of about 2 1/2 hours and duration of about 6 hours BUT by being delivered in small aliquots hour by hour the effects are stretched out.
I wish you well in sorting through your adaption to exercise, and suggest you plumb the expertise of your doctor and dsn.
