Hey there. I replied a bit on your post over in the OmniPod area, but I'll reiterate that shots made it impossible for me to run, and the pump made me able to run at least as well as I was running 20 years ago before my daily injections started trying to kill me during exercise of any effort.
I'd say do at least a couple of days of no exercise/no food to zero in on your ideal basal rate in the absence of other factors. The thing that you worry about is that you are actually taking too high a basal rate during the day and the exercise in combination with that will lead to a severe low. You don't want your head to break your fall again, right? Running for anyone is a matter of balancing fuel and effort, so you will want to keep enough fuel onboard to finish your races. The thing I think is happening to me is that my BG falls rapidly during exercise, but that means it is being used by the muscle cells. When I stop exercising, it bounces back up.
I did a 10K back last August that ticked me off because within a half an hour after I finished, I was up over 170. So annoying. Pre-running fueling has been pretty good for me, crossing the starting line between 150 and 200 on the BG meter. You may want to look into a CGM, as well, to monitor things in motion without having to stop to do fingersticks.
Good luck. I'm at a similar weekly mileage, maybe a little less, depending on my next race, and have been having pretty good results without a lot of fussiness. I don't start running over 250 or under 80, but otherwise I think my body is pretty used to me taking off for a few miles a few times a week without throwing a huge fit.
Nah. Your body's reaction to exercise is pretty trained. I started again from scratch and it took a while to really get to a steady-state running process, but once you make sure your basal is okay for a run without additional fueling (or with a set quantity of fueling), then everything else is easily adjustable in the moment. Or at least within 15 minutes or so.
Yes, I have to agree with DEA- your body will adjust pretty quickly. I'm 36 dx 16 years ago. I go on and off the pump over the past 13 years and there's just minor changes in the way you adjust your insulin for a run. With a pump, I would decrease my basal temporarily for sometimes 1 1/2 hours before I ran, vs with shots I take a bit less for the meal or snack before the run. Always, though, for me I need to decrease overnight insulin, it effects me there the most. I don't do long runs though, reading through some of these posts it seems like more planning is involved in longer runs (over 10 miles)