A few things really (a couple you have mentioned)
-You're allowed NO sugar (cakes/biscuits/sweets)
-You're not fat, yup a common one
-"So do you wee a lot" (ok not totally myth on diagnosis but to think it happens all the time, errr no)
-You must be hyperactive a lot. (This is obv link to the whole feeding a kid too much sugar and them being hyperactive)
-They always think you're destined to have cataracts/amputations
...I'm sure I will think of more at some point.