Kenneth Bae, a Korean-American missionary detained in North Korea for the past nine months, has been transferred from a labor camp to a hospital, CBN News reports. Meanwhile, in the United States, his family is stepping up calls for his release. On Saturday, hundreds of people attended a vigil for Bae in Seattle, Wash. Bae, a tour guide who encouraged prayer for the reunification of South and North Korea, was arrested in November 2012 and sentenced to 15 years of hard labor. His sister, Terri Chung, said Bae suffers from diabetes, an enlarged heart, liver problems and back pain. "What if something happens to Kenneth -- he goes blind or his heart gives up or his body just gives out," she said. "He's in a really weak state. He's got to be in a bad state for them to have transferred him." In recent letters, Bae urged his family to speak out more for his release.