Have mercy, Nick Jonas!

Actually, the 'Mercy' tattoo on his arm was pretty much the only part of his upper body missing from the sexy pic the youngest of the Jonas Brothers posted this afternoon (July 30) on Instagram and Twitter! The 20-year-old was quick to explain why he was sharing the rare shirtless image, crediting a rigorous routine of diet and exercise that helps keep his diabetes in check:

 

Nick was diagnosed with Type 1 diabetes when he was 13 and is an active spokesman and fundraiser for organizations fighting the disease, along with several other youth charities, including the Trevor Project and the It Gets Better Campaign.

"I want to inspire all young people, whether they’re diabetic, being bullied, or just having a hard time at home," he said in an interview last year. "Dealing with diabetes has been tough, but I’ve also been so blessed, and I feel I can give real encouragement and inspiration to young people dealing with similar issues.”

Wonder how many people will be inspired to hit the gym after checking this pic out!