Whether "Dragon Ball GT" is "canon," or part of the "official story," is a subject of fan debate. As of 2014, no definitive answer has been reached. Although "GT" is not based on the "Dragon Ball" comic book, the series' author, Akira Toriyama, is a credited author of the show.
Toriyama wrote the original "Dragon Ball" comic book, which was adapted into two different television shows, "Dragon Ball" and "Dragon Ball Z." While "Dragon Ball GT" is not based on his comic, Toriyama oversaw production of the show and helped design elements of it, including the main cast and logo.