Lee Da-chu, deputy head at the Taipei Detention Center in Tucheng where Chen was being held, said Chen had complained about chest pain. He also said the former leader's pulse and blood pressure were unsafe, adding that Chen has refused to take medications prescribed to him, the Taipei Times reported Sunday.
Officials said Chen was taken to the hospital for a check-up and possible force-feeding.
Chen is suspected of money laundering, accepting bribes, forgery and embezzling about $450,000 during his two terms in office.
He has been held incommunicado without charge, the newspaper reported. He has accused the Chinese Nationalist Party of "political persecution" and waging a "political vendetta" against him in order to curry favor with Beijing.