Nick Jonas shocked by topless tweet response

Nick Jonas has been left shocked by the feedback he received after posting a topless self-portrait online, insisting he didn't expect the shot to become a talking point.

The diabetic pop star and actor looks ripped and toned in the photo that he insists wasn't an impulse 'selfie', but admits he's glad that most of the feedback has been positive.

He says, "I debated (posting) it with my brothers and people in our band. I was like, 'Should I do this?' and they were like, 'You have to!' So I did it... I don’t know if it’s something I’d do again.

"There’s a lot of people running around without their shirts on these days, so I just didn’t want to add to the noise, but I felt like, as a diabetic..., it’s twice as hard for us diabetics to stay in shape.

"I’ve met a lot of diabetics recently who have come to me and said, ‘Thank you for being so vocal about fitness and health’ - because it’s helping them. I just wanted to give some inspiration to those people... It’s been a pretty hilarious reaction."

Jonas told Los Angeles DJ Ryan Seacrest he has been working out hard in recent weeks so he looks good for a series of upcoming love scenes with actress Isabel Lucas in the movie Careful What You Wish For.

He adds, "I wanted to look OK.”