Nick Jonas felt under "pressure" to look perfect.

He said: "I never struggled with addiction on any level, which I think probably stems from living with diabetes. I'm not saying that I haven't had one too many drinks one night, but I think the thing that was most challenging for me was applying a lot of pressure to myself and trying to maintain a real image of perfection, which is so impossible. And we did have a lot of pressure on us to maintain that image.

"But once you become an adult you realise nobody's perfect, and it actually does you a disservice in your artistry to try and keep that up ... But it was more challenging than I've spoke about before."

And the 23-year-old singer also opened up about the time he felt his career was "over" when he was just 21.

He told Entertainment Weekly magazine: "I never wanted to sound like I was bitching about it, because a lot of people would kill to have what we did. But I had a couple of years where s**t was really not going well - like when the Jonas Brothers tried to come back and do it again, but too many things were just not authentic about what we were doing.

"To be 21 and think, 'All right, is my career over? Have I blown it? Or do people just not care?' There were a lot of questions and self-doubt to a point where I was considering, 'OK, I'll just write and produce music for myself.'"