Hi Hazel,
I would suggest as birthdays only come but once a year, let your child pick what ever cake he/she wants, just make sure he/she doesn't scoff the whole lot! Type 1 diabetes is a lot for a child to deal with, and its still early days for you. (i have a 10 yr old son T1, for almost 3yrs) If they're having a party they'll soon run it off, if not you can always combat any highs with fast acting insulin. What regime are they on? i would be happy to help any way i can, Take care
Suzi x