Kenneth Bae , the American citizen sentenced to 15 years in a North Korean labor camp , has been moved to a hospital after a serious deterioration in his health , his sister said . Detained in North Korea in November and sentenced in April for `` hostile acts to bring down its government , '' Bae is now suffering from severe back and leg pain and has lost more than 50 pounds , his sister Terri Chung told CNN late Sunday . Chung said she received the information from the U.S. State Department , which told her the Swedish ambassador to North Korea had visited Bae in the hospital on Friday . Sweden represents U.S. interests in North Korea because the United States has no diplomatic presence in the secretive state . Detention in North Korea has taken a heavy toll on Bae , who had already been dealing with other health problems , including diabetes . `` I think the last three months in the labor camp have certainly been very trying on both his mental and physical health , '' Chung said by phone from the Seattle area . Bae from North Korean prison : Please help me . 'Tremendous ' stress . The eight hours per day of farm labor , which Bae had never done before , appear to have worsened his symptoms , she said , adding that `` he 's also under a tremendous amount of stress . '' Other problems he 's suffering from include kidney stones , dizziness , blurred vision and loss of vision . The family is `` extremely concerned '' about the situation and is pleading with the U.S. government to help Bae 's case , Chung said . U.S. officials have repeatedly called on North Korea to release Bae , whose sentence was announced toward the end of a period of heightened tensions between the two countries . The State Department called for Bae 's release again in a news conference Monday . `` We continue to urge the DPRK authorities to grant Mr. Bae amnesty an immediate release , '' said Marie Harf , the department 's deputy spokeswoman . `` It 's clear that Mr. Bae 's health is deteriorated . We 've been concerned about his health for a long time , and is of deep concern to us today . But Kim Jong Un 's regime has so far showed no sign of budging on the case of Bae , who they call Pae Jun Ho . There did n't appear to be any recent articles published about Bae by North Korea 's state-run Korean Central News Agency . Hoping for release . In a video released early last month , Bae appealed to North Korean authorities for forgiveness and asked the United States for help in securing his release . `` Although my health is not good , I am being patient and coping well , '' Bae said , his head shaved and his face noticeably thinner than in earlier photos . in that interview , he spoke of health problems including diabetes , high blood pressure , fatty liver and a back problem . `` I know what I did is not easily forgivable , but I hope that things will work out so that I can be with my family again soon , '' he said . Chung had previously said that Bae is the owner of a tour company and was in North Korea for work . North Korean state media have detailed the reasons why Bae was sentenced . Among the list of alleged crimes was setting up bases in China for the purpose of `` toppling '' the North Korean government , encouraging North Korean citizens to bring down the government and conducting a `` malignant smear campaign . '' State media also say that Bae had planned what it called a `` Jericho operation '' to bring down North Korea through religious activities . They have suggested that Bae could have been sentenced to death , but avoided it through `` candid confession of his crimes . '' Sister : 'He 's not a spy '
Three months of manual labor have taken a toll on Kenneth Bae 's health . He was sentenced to 15 years in a labor camp in April . His sister says he was moved to a hospital after his health deteriorated . He 's suffering from leg and back pain and severe stress , she says .