Diamond is now promoting A Beautiful Noise, a Broadway show about his life and he admitted it was “pretty hard” to watch the production.
He said: “It was all pretty hard. I was a little embarrassed. I was flattered, and I was scared.”
Asked what he was scared of, he replied: “Being found out is the scariest thing you can hope because we all have a façade. And the truth be known to all of ‘em. I’m not some big star. I’m just me.”
It comes after the star reemerged from retirement to surprise fans with a rare performance at the broadway show.
The performance was eagerly welcomed by fans who immediately took to their feet as he performed Sweet Caroline with his wife Katie McNeil by his side.
The performance was made even more special as he has rarely been seen in public since his diagnosis.
When the singer announced his retirement from touring five years ago due to his diagnosis, he insisted it wouldn’t spell the end for his career.
He said in a statement at the time “I plan to remain active in writing, recording and other projects for a long time to come.
“My thanks goes out to my loyal and devoted audiences around the world. You will always have my appreciation for your support and encouragement. This ride has been ‘so good, so good, so good’ thanks to you.”