Before leaving for South Africa on Friday, Diyab had gone on a 68-day hunger strike to demand relocation from Uruguay to an Arab country, closer to his wife and children.
"I didn't want to do this hunger strike, but they closed the doors and left me with no solution, and this was the only solution I found," Diyab had told CNN in September. "I need to live a normal life with my family, my children. This is what I need."
Diyab's family is currently in Turkey. He told CNN that the Uruguayan government had said his family would come to the country, but never followed through to make it happen. His family now refuses to come to Uruguay.
"I started [the hunger strike] after speaking to the government multiple times, without finding a solution," said Diyab, who is also known as Abu Wa'el Dhiab
"I'm not doing this to die. I'm doing this so that I can meet with my family in a different country that is not Uruguay. If I die, the responsible parties will be the U.S. and Uruguay."
The Uruguayan government has said it has tried to find a country willing to take Diyab.
In October, a statement on the Facebook page titled "Vigil for Jihad Diyab," maintained by his supporters, said that "with his health already very affected, he received an offer to travel to another country." It had not mentioned which country Diyab would travel to.
How Diyab ended up in Uruguay
Uruguay received six Guantanamo detainees, including Diyab, in 2014 as a move to help President Barack Obama's administration close the detention center in Cuba.
According to Department of Defense files, Diyab was arrested in 2002 by Pakistani police during a raid on a safe house in Lahore and was known to have ties to al Qaeda militants. He was never charged and cleared for release in 2009.
It took five years for the United States to find a country willing to take him.
Diyab and the other detainees have been very vocal about their unhappiness in their new homes in Uruguay, saying they felt alienated in a country where they did not speak the language and there is no Muslim community.
They have complained that the government had not been doing enough to help them get jobs and that they continued to be separated from their families.
Earlier this year, Diyab escaped the country, but was captured in Venezuela and returned to Uruguayan authorities.