Hi Susan,
Just mention it to your waiter/waitress, if you are eating in a full-service restaurant. Most counter-service (fast food/snack stops) have regular "brand name" items that you should recognize. They may even have some items especially for sugar-restricted/sugar-free diets that are not up on the signs ... you do have to ask.
My DH has to have sugar-free ever since his Gastric By-pass. (Most people get over the sugar sensativity w/in 3 months, my DH seems to be stuck with it for life.) When we went to
WDW, the waitress in Crystal Palace went back into the kitchen and brought out a bowl of sugar-free ice cream for him (sweetened w/Splenda) and some Tofutti for DD (lactose intolerant); they felt SO special to be able to have ice cream with DS, other DD, and me!
Most Disney Castmembers (at either
DL or
WDW) are willing to go the extra mile for you to have a good experience. All you have to do is ask!