I cycle to work everyday working day, 15 km's one way, without breakfast, I need 1 unit of humalog to keep things steady. I've recently been on vacation in the UK and was out running up hills every morning 10 - 12 km's in around 1 hour, again without breakfast. Didn't bother with insulin for the hill running though. I find exercise in the morning tends to have little effect on my blood sugar , occasionally raising it , however in the evening it can drop it dramatically.