According to Larry Brown Sports, Glen Rice had a fling with the former Governor of Alaska back in 1987 while he was in college at Michigan.

An author named Joe McGinniss has a book coming out about Sarah Palin called The Rogue: Searching for the Real Sarah Palin. In this book one of the things he covers is that she had a one night stand with former NBA All-Star Glen Rice.  This part of the book was leaked by the National Enquirer.

Sarah hooked up with the NBA great, then a 6-foot-8 junior at the University of Michigan when he was playing in a college basketball tournament in Alaska in 1987.

-Excerpt from the book

The book also notes that this fling took place just nine months prior to Palins wedding to her husband, and that he was dating her at the time of it.  So did Sarah Palin really have an affair with Glen Rice while he was in college?  Only her and Rice know the answer to that.