Like many girls who grew up in the ’90s, journalist Masuma Ahuja often found her own experiences reflected in Ann M. Martin’s series “The Babysitters’ Club.” Her favorite character was the effortlessly polished Stacey McGill, but not necessarily for her style or New York City roots: Stacey, like Ahuja, is a Type I diabetic, and, as a child, Ahuja didn’t know anyone else her age who dealt with the day-to-day complexity of the disease.