I don't know if sugar can cause diarrhea or not. I do know you are supposed to avoid sugary foods when you already have diarrhea, so maybe? I don't know if that's associated with GD. I had a bout of something just like what you're describing around maybe 17 weeks. (I can't remember exactly when it was now.) It just went away after a couple weeks. I didn't worry because I didn't have a fever, rash or any other symptoms, was having some normal stools, wasn't dehydrated, wasn't going several times a day, etc. Pregnancy does all kinds of weird things to your body and I just chalked it up to that.