Demi Lovato's Little Sister Celebrates Singer's Birthday With Emotional Tribute On Monday, Lovato turned 26 years old and her sister, Madison De La Garza, celebrated the singer's life. To commemorate the occasion, she shared a cute throwback photo of herself and Lovato on Instagram. Madison De La Garza, via Instagram Madison De La Garza, via Instagram De La Garza's heartfelt message comes a month after Lovato was rushed to the hospital for an apparent overdose. Lovato is now getting help for her ongoing battle with substance abuse.