Using temporary basal for excersize

whenever i go out for a healthy walk, i set my pumps temp basal rate from 100% down to (first 75%, then 70%, then 65%,and 60%) 50%. i am trying to figure how low i need to set my temp basal in order to not go low while i am out walking. i go out for btw 1&1/2 to 3 hours and walk at a swift pace. but its not like i am burning up a sweat.its fall in NYC and its brisk out.i bring my glucose tabs with me, and i bring some candy. still i cant seem to get my percentage right; i inevitably go low, from a normal, healthy 120 down to a frightening 45. i stop, have some sugar, and rest for 15 minutes, check my BS again, and then seeing that they are coming up, and i am out of the "danger zone" i can resume my walk. however, its not long before i go low again. does anyone else have this problem when they excersize? should i be eating lunch before or after i go walking? should i just take the pump off while i excersize?

any suggestions are welcome. i want to enjoy the Fall season as much as possible!

Usually I find that I need to back off well before I want to exercise, especially if I am out away from home and do not have all the readily available items close at hand to raise my sugars. I will often skip a bolus for carbs eaten 15 to 30 min prior to exercise to allow my sugars to increase or stay stable while exercising, I just have to watch post exercise as I have a big tendency to have a rapid increase in my blood sugar if i do not bolus then. (trial and error!) I have also bolused only part of the full amount depending on timing of food and exercise - again, to allow a somewhat higher than normal sugar that will be covered during the increased activity. I have entered temp basal rates at a -90%, this is so I don't forget to resume - again depending on length, type, and potential carb load before and during activity. Again, trial and error. Usually I am most successful with carbs on board not covered by the appropriate amount of insulin, correcting after I have completed whatever exercise I choose to do. Good luck!

I try to exercise when I haven't eaten or insulined for a couple of hours, at least, and my pump doesn't have much, if any, insulin on board showing. I suspect there may still be some but, if there's no insulin, 5-10G of carbs/ 20 minutes of running will usually cover me pretty well. For longer excursions, I'll switch to 50% as I start off, or maybe while I get ready, which takes 15-20 minutes to get my stuff together.