Firstly, there is no confirmation that type 1 is lifestyle related - you have not eaten too many Krispy Kremes and you can eat more (provided you carb count and inject).
However, I like your idea of mixing the birthday treats up a bit. If you want to have something lower carbs, then cheeseboard is a good idea ... although the higher fat may put some people off; you could stick with the savoury theme and go for some antipasta type with olives and hummus and carrot sticks; I've seen some people provide sushi but that could be a risk as some people don't like the idea of raw fish; if you are just interested in knowing the carbs then most packaged cakes are suitable; if you want something slightly less sweet, you could bake something yourself and reduce the sugar (something I often do); or you could provide a large bowl of interesting fruit (but you'd have to do a little research on carb content beforehand ... just Google "carbs in <x>")