I have oats mixed with some whey, about 1 hour before going to the gym. Its something that is easy to digest, and won't bother me during my workout. I don't like working out hungry, but working out on a full stomach is just as bad. Dextrose might be absorbed too quickly, but it'll probably be good if you take it right before, or during your workout. And like Java said, mix it with some whey.