J.P.
Our son was not willing to be potty trained - at all. We never gave him sugar...literally, but I even tried bribing him a cookie. He'd hand it back to me and tell me to put it back in the pantry. NOTHING worked.
We started telling him that when he turned 3, he didn't HAVE (rather than GET) to wear diapers anymore. So, when he woke up on his 3rd birthday, we took him out of diapers. He had 7 "accidents" that day - to make up change our mind. He even went in and sat on my pillow and soaked it. He was dry at night the first night, but his pull-up at night became progressively wetter, so we put him on a pad on his bed at night and a pair of underwear. No accidents. In fact, within the week, he was potty trained - no accidents after that.
He saw that we weren't going to budge AND he wanted to go to school, so we told him that kids in diapers can't go to school.
I've known a few kids to go to chiropractors and get their sacrums (low back area) adjusted to help with bed-wetting/bladder control, etc. if that might be a component?