I don't think it's going to matter as much what you do off the bike toward cutting out sugar in your diet.
But for what you eat and drink while on the bike, if you expect to go for more than an hour and a half and hit some hills at a good effort or put intervals into your ride, then you'll need some carbohydrate during your ride.
There are easily absorbed carbs and not so easily absorbed carbs. Some have a bigger effect on glycemic index and other things if you are worried about that.
IMO, diet on the bike and diet off the bike are two different discussions. So make certain you know which you are asking about and which is being talked about.