@Pianoplayer7008’s Emily’s Walking Thread reminded me of an interesting BG property of walking, that we discovered a few months ago and that we find really useful.
Several months ago, we took our T1D pre-teen to DC for a 5 day week-end. Every day we walked a lot, probably 5-6 hours or more of sustained walking. He did not drop while he was walking, but, after each day, he would drop of lot due to the muscle/liver/kidneys refueling process.
So, the 3rd day we decided he would try to refuel as he walked. We did not know what ICR to use, so we decided to have him eat some carbs without injecting. That day, he ate close to 30 carbs without going up (or dropping) and without having to bolus. That evening, he did not run half as low as before. The next day, he went up to 45 carbs during the day, in batches of 4-9 carbs, even with a half-banana at one time, and without injecting. And he did not run very low that evening.
So now we know that, when my son walks on a sustained pace for long periods, he can refuel on the go without having to inject, and, if he does that, he won’t run significantly low after exercise. So he can be a kid and get some sweets from a vendor as we walk around without having to wait another 45 minutes… It is refreshing to find one thing where he can just be a normal kid.
@Eric, can you explain exactly what makes this possible – being able to go without bolus in such an activity?
Yes, without having to bolus, but he did have insulin for those carbs in the form of basal insulin. So that basal insulin was acting on the carbs and was amplified because of the activity. A few details on that in a moment.
Yes, all the carbs consumed during the activity are being used to fuel the activity in addition to the muscle glycogen and fat. The body uses any of the fuels available in the most efficient way. Carbs being digested are available and used right then. This reduces the post-activity hypos! Joslin-LowAfterPhysicalActivity
In the same way that insulin increases the GLUT4 translocation to the cell membrane and increases glucose uptake, muscle contraction and exercise also increase glucose uptake into the skeletal muscle. During exercise, skeletal muscle glucose uptake is increased greatly.
The various ways in which muscle contraction and exercise increases glucose uptake into the muscles is not totally understood, but it is believed that many overlapping pathways exist which provide redundancy. Essentially this is thought to be one of the reasons why glucose can be used with much less insulin during exercise, and immediately after exercise. I will hopefully be able to post some more details on this topic soon.