Another artist with a connection to a Fox music competition show is heading to Glee.  Following the news that Adam Lambert would appear on the show's upcoming season, X Factor judge Demi Lovato is also joining the cast for a "significant arc," according to

According to TVLine, Demi, who's been focusing on her music rather than her acting in the last few years, will play Dani, a struggling artist friend of Rachel and Santana's.  She'll interact with Adam Lambert's character, who's been described as "Kurt's nemesis" and they'll perform together as well.

Demi will appear in at least six episodes, beginning with the one airing October 3.  Her shooting will be scheduled around her X Factor duties, TVLine reports.  This is the singer's first major acting role since her Disney show Sonny with a Chance went off the air two years ago.

In other Demi Lovato news, she turns 21 on Tuesday, and she has a lot to celebrate.  After overcoming personal struggles and bravely sharing her story with fans, her career has never been hotter.  Not only is she about to start her second season on The X Factor,but her current album, Demi, continues to churn out hits, the latest being "Made in the U.S.A."

A huge part of Demi's career resurgence can be traced to her previous album, 2011's Unbroken, which announced her return to the scene after she took time out of the spotlight to enter treatment.  That album's lead single, "Skyscraper," became her first platinum single and last year, it won her the MTV VMA for "Best Video with a Message."  Though it documented Demi's personal journey, it's became an anthem for fans who were struggling with their own difficulties.

"I can't even fathom how it's helped a lot of people," Demi said "I hear so many people, they come up to me and say things like, 'You saved my life' and 'You inspired me to get help,' and that just blows my mind."

Demi says that helping people through her music is something that's very important to her.  "You know, it's not my duty and I don't feel like I have to do it.  I just want to," . "I feel like there's more to life than, you know, just singing and I feel like God gave me a voice for a reason, and I want to help people with it."