Gomez, 18, says in the statement that she is standing by Lovato no matter what happens.
According to HollywoodLife.com the statement said: 'Demi is my best friend and I don't care what has happened recently in the past. I feel like a horrible friend for not being there for her or acting like I haven't been there.
'I recently visited with her and I'm glad she is seeking help and I hope that it gets better for her.'
She added: 'I knew this time was going to come, but I didn't think it would happen this way - I love Demi with all my heart and wish her the best of luck and I definitely am standing by her side no matter what happens.'
Teenage star Demi, 18, entered a treatment centre on Monday for 'emotional and physical issues'.