Gossip Girl star Michelle Trachtenberg‘s cause of death has finally been revealed.
Laboratory tests showed that the 39-year-old actor died as a result of complications from diabetes mellitus.
Deadline reports that her death from natural causes was announced by the New York City Office of the Chief Medical Examiner.
Diabetes mellitus is a disease that results in blood glucose levels rising too high because the body doesn't produce enough insulin, or is unable to use the insulin it produces effectively.
The condition is associated with several health problems, including heart disease, strokes and nerve damage.
Trachtenberg, who was also known for starring in Buffy the Vampire Slayer as Buffy’s younger sister Dawn and leading the 2005 Disney movie Ice Princess, was found dead in her New York City apartment by her mother.

Police responded to a 911 call just after 8 a.m. on February 26 at One Columbus Place, a 51-story luxury apartment complex on Central Park South.
The NYPD confirmed they found Trachtenberg “unconscious and unresponsive,” and she was pronounced dead by emergency medical workers. She had reportedly recently undergone a liver transplant.
Trachtenberg was born in New York City on October 11, 1985. She made her first television appearance at the age of just three, appearing in a commercial for Wisk detergent. She would go on to star in over 100 commercials as a child actor.
At the age of six, Trachtenberg landed her first appearance in a 1991 episode of Law & Order. At the age of nine, she won her first credited role as Nona Mecklenberg on the Nickelodeon series The Adventures of Pete & Pete, a part she would play from 1994 until 1996.
That year, she began her film career with the title role in Harriet the Spy. In 2000, she secured another breakout role as Dawn Summers in the hit series Buffy the Vampire Slayer. She remained on the show until it ended in 2003.
Trachtenberg had first met Buffy star Sarah Michelle Gellar when they worked together on soap opera All My Children. She told the BBC that she had dreamed of being cast in the show before landing the role of Buffy’s younger sister. “I kept in touch with Sarah through the years, and because Buffy had become my real favourite show, I had always tried to think of ways for me to guest star on the show, and I heard about the call one day,” she said. “Sarah was always very supportive.”
She played the lead role in Disney’s 2005 comedy sports drama film Ice Princess as Casey Carlyle, a science whiz torn between a future in academia and her dream of becoming a professional figure skater.
Perhaps Trachtenberg’s most well-known role was as antagonist Georgina Sparks on the CW TV show Gossip Girl, which ran from 2007 to 2012. She recently returned to the part for appearances in two episodes of Max’s Gossip Girl revival.