Sugar is inflammatory, so that may explain the arthritis flare-up. There is some great coverage of the topic of what sugar does in Neal Barnard's book Foods That Fight Pain. I have a real weakness for sweets--chocolate, peanut M&M's, Boston Baked Beans, Lemonhead, etc. I have not noticed a short-term effect like some of you have. But have noticed a long-term improvement with improved diet. I can't narrow the improvement down to avoiding sweets. Fat and/or meat seems to play a role in it for me. Stay strong, it's hard.
Ron