Hi
@Libby3781, The following from my experience as a T1D, not as professional opinion or advice. Seeing your DSN sounds like a great idea to work out the best way of managing your exercise, food and insulin.
1) ask the club for the best type of running shoes and try them on to ensure they fit well enough (a bit loose first thing in the morning but comfortable after walking around on carpet all day.) By doing that you have a chance to see if you are still comfortable when your feet swell and can still return them to the store if they are not suitable. Prevention of rubbing spots etc is important. When I walk I wear two pairs of socks so that there is more protection of the skin of my feet and it is better for the socks to rub against each other than my skin rubbing as much.
2) wear suitable clothing which reduces the risk of over heating or becoming too chilled and allow for the sun (e.g. waterproof sunscreen), weather (? googles etc for blustery days) etc
3) by testing my BSLs before and at the end of exercise I was able, after several measurings, to confirm that my BSL rises with exercise and drops later.
4) I have heard of others where their BSL drops during exercise and still others whose BSL do not to change much during this time.
5) with BSLs rising during exercise I dd not eat before exercising as this just raises the BSL higher. I reduce my insulin that is acting through the exercise time until at least 6 hours after. usually 20 to 30% depending on the degree and length of exercise.
I also pay close attention to the my BSLs
6) I have heard of others who reduce their insulin a bit and also eat before exercising (fluids etc with some glucose but not cream buns etc)!!! as their BSLs drop or do not change much. The warning about the later BSL drop still applies.
Best Wishes for a fun time !