Diabetes cured through diet and exercise?

I heard a story about a boy who had diabetes at a young age because of genetic reasons. He had maintained an excellent diet his whole life and was on the wrestling team his freshman year of high school. Just a few weeks into wrestling season he was cured from diabetes and his body began to function as it is suppose to. I don't know if this is a true story, but could it be possible? Is diabetes curable through diet and excercise?