You could always give out candy that you personally don't like, that way you won't want to eat it, hahaha! This year I went with smarties and lollipops so that the leftovers could be used for lows (smarties are made of the same stuff as glucose tabs but they taste better and have a better texture). If you do buy candy that you like, just bolus for it and enjoy yourself. Halloween comes once a year and it won't hurt you to treat yourself
I was diagnosed in the 80s and we were not allowed to have the candy at all back then. This made Halloween a guilt filled time of year for me as I would sneak candy and end up super high. This was before the days of carb counting.