If you're talking about during the brewing process, then you should just have a higher OG, and it could still ferment down close to the recipe's original target FG... What kind of sugar did you add to the recipe? That will impact any flavors you'll get, as well as if it will actually ferment. Things like lactose won't ferment, so the brew will be sweeter than the recipe originally would have produced. If you added an actual surgar that can be fermented, then you're probably going to be ok.