Demi Lovato has thanked her supporters after she revealed she has broken her six year sobriety milestone.

The 25-year-old musician recently opened up about her battle with drink and substance addiction when she released her new track 'Sober', in which she reveals she has relapsed after celebrating six years of sobriety earlier this year.

And now, in a new Instagram post, she has thanked the people who have never left her side in throughout her turbulent battle with addiction.

Posting a video from a recent concert which includes the packed crowd cheering for the singer, Demi wrote: ''To my fans, my family, and my supporters, the ones who never left me, you are my light. I am forever grateful (sic)''

The 'Sorry Not Sorry' singer released the surprise track last week, in which she alludes to having relapsed as she sings: ''Mama, I'm so sorry I'm not sober anymore, and Daddy please forgive me for the drinks spilled on the floor.

''To the ones who never left me, we've been down this road before. I'm so sorry, I'm not sober anymore.

''And I'm sorry for the fans I lost who watched me fall again. I wanna be a role model but I'm only human.''

Demi has been open publicly with her battles with addiction - and her stint in rehab in 2010 - and emotionally celebrated her six year milestone during a concert in March.

The following month, she was snapped drinking from a red cup at Hayley Kiyoko's album release party - but she was quick to shut down her critics who doubted her sobriety.

She replied on social media: ''I don't have to defend anything but it was red bull.''