Thomas became one of the first international rugby stars to come out as gay, saying at the time: "What I choose to do when I close the door at home has nothing to do with what I have achieved in rugby."
Apart from waking up at 6am every day to take a pill and visiting the hospital every six months for blood tests, the condition has little impact on Thomas' day-to-day life, he told the BBC.
Thomas admitted that revealing the diagnosis was similar to his experiences when he came out as gay because of "the fear, the hiding, the secrecy; the not knowing how people are going to react".
"But I think when it was all about my sexuality it just seemed like there was more empathy and more understanding because you had more knowledge, because you could turn on the telly and you could see that there was LGBT representation on most platforms."
Thomas won the Heineken Cup with Toulouse in 2005 and captained Wales to their first grand slam in 27 years in the same year. He won his first Wales cap in 2007, before announcing his retirement in 2011.
In 2018, Thomas was the victim of a hate crime after he was assaulted in Cardiff, allegedly because of his sexuality.
Thomas lives near Bridgend with his husband Stephen, 56, who he married in 2016. "I'm going to have to take it on board and deal with it," Stephen, who does not have HIV, says in the documentary.
"I think it's going to teach so many people what HIV is.
"I was one of the ignorant ones, I will be honest, like so many people."
