It was recently announced that Elton had praised Russell T Davies' Channel 4 drama for its ''incredibly moving account'' of the AIDS crisis in the 1980s.
It's A Sin follows the lives of four friends living together as the HIV/AIDS crisis emerges in the UK.
Elton said that it brings back sad memories of when many people were ignorant and cruel.
''Thank God we have come so far since then.
''Hats off to Russell T Davies for creating this moving testament to a pivotal moment in LGBTQ history.'' He also said the cast was ''sublime.''
On yesterday's BBC One's Morning Live, Russell, a multi BAFTA-winning writer, revealed that Elton had personally called the cast.
''He phoned them up to congratulate them. That's the man who's raised half a billion pounds for AIDS research, so that was the ultimate compliment, I think. That was the ultimate reward.''