I am now on a low-sugar diet and my joints are still doing well. When I eat some sugar after half an hour my wrist and elbow start to hurt again.
I have tried this a few times and the effect is totally reproducible. This experience makes me wonder how many people who have arthritis and other inflammatory diseases could reduce their symptoms with a low/no sugar diet.
Keeping weight off is also much easier with low sugar.
My advice is: Keep it a try. Stay off sugar for a month and see if you notice any changes. There is nothing to lose (besides a few pounds).