Type 1s - Does anyone increase bolus for exercise?

phoenix said:

I think there are 2 considerations here.
1) exercising after fasting
2) high intensity exercise causing glucose to rise (ie immediate need for glucose)
(and the two are compounded)
Theoretically, I think that if your basal was perfect then you could exercise before eating without anything to eat.
I have a pump and whatever I do. I still find that I get a rise if I don't eat and bolus something before exercise.
Anaerobic exercise also makes glucose levels rise, indeed a short sprint is recommended to pre-empt a hypo. The liver reacts by producing glucose.

I won't exercise fasting and I won't normally exercise within 1.5 hours of eating; it is restrictive but I haven't found a solution. When I go for multi day, long distance walks and set out after breakfast , I inevitably have to eat something within an hour of setting out.

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I haven't read the Volek book, I have read most of his research and it always seems to me that there was nothing left in the tank after low carb exercise. His bicyclists would not have been able to sprint. He uses very small samples and it seems that the averages mask what happened in individuals. Cassandra Forsythe who worked in his lab wrote :

I posted this quote some time ago, the link is now dead (I'll try a search)
Found it: it's a very long discussion and obviously not to do with people with diabetes of any sort but interesting all the same.
http://jpfitness.com/index.php/foru...-protein-or-carb-reduction?limit=30&start=120

Click to expand...

Hi Phoenix, @brett and @noblehead ,

Thanks for your input - particularly with regards to your own experience of BG rise when you have an empty stomach, or first thing in the morning. I have heard of many who much like @ElyDave don't suffer with this phenomenon, so it's useful to hear when others do.

May I ask what you have tried to counter this - such as taking even a small handful of nuts before you exercise? Do you have to eat carb or have injected/infused insulin? (I can understand why this might be the case, as minimal insulin levels in the body are one of the triggers for the liver to release glucose - so a higher level = no release)

In many respects I can understand that exercising first thing in the morning could compound the rise through dawn phenomenon, but would you observe a BG rise even with moderate exercise just because you have an empty stomach?

Sorry for the questions! I am just trying to get my head around this - as I say, it seems to me that a lot of this phenomenon is experiential, but as yet I haven't found anything recorded and evidenced which is frustrating - (perhaps you could point me to something if you know of any research) I would be very grateful for any input.

In order to determine if @oldgreymare is suffering from a BG rise from not only the exercise intensity, but also by exercising on an empty stomach or exercising first thing in the morning (and so make adjustments that could help get better BG control) should she already be experiencing a significant BG rise every morning? (I'm just wondering if a significant dawn phenomena is an indicator that this can be a problem)
@ElyDave, what's your experience on this?

(Apologies for going down a bit of a rabbit hole here)

Bebo, I always inject and eat within 20 mins of waking so avoid the liver dump. When I fast for a cholesterol check my bg starts to rise around an hour after waking and increases throughout the morning, I never miss breakfast as a rule as I think it's the most important meal of the day, if I was a runner then I probably would just eat something light and inject a unit or two to avoid the stomach cramps, however the most I would do with regards to exercise is walking or a slow bike ride, both of which don't seem to be a problem after eating breakfast.

Eeek - that's a pretty erratic waking BG, were you able to understand why you got the results you did though? If not, it sounds like you would benefit from a trial on CGM (continuous glucose monitor) - it would help enormously with refining your insulin requirements with exercise too.

It is possible to manage blood glucose rises from 'liver dumps', the frustrating thing is though that there is no 'one size fits all' solution. Two people can do exactly the same bit of exercise, and where one will get a BG rise, the other may remain completely level.

It sounds as though you are looking at doing all the right things though - adjusting with short acting insulin after you finish will definitely help. It will just take a bit if trial and error to get it right (and even then there will no doubt be odd surprises!) I think the thing is to adjust in tiny steps, and keep refining as you go - that along with collecting your data so that you can look back to see why and when things did or didn't work.