Michelle Trachtenberg lost her life aged 39. We now know what happened.

We knew and loved her as Georgina Sparks causing trouble on Gossip Girl and Buffy's sister Dawn Summers in the American supernatural drama. Or maybe she first captured your heart in Harriet the Spy?

Tragically in February, actor Michelle Trachtenberg died, aged 39. Now, her cause of death has been revealed, nearly two months on.

The former child star was found dead at her New York City apartment on February 26, People reports.

Police responded to a 911 call at about 8am on Wednesday (local time) and found the 39-year-old "unconscious and unresponsive".

She was declared dead at the scene.

At the time, police sources told ABC News she recently underwent a liver transplant and may have been experiencing complications.

Her cause of death had initially been ruled "undetermined" after her family objected to an autopsy.

Now, we have confirmation.

The Gossip Girl star died from complications from diabetes mellitus, the New York City Office of Chief Medical Examiner confirmed to Page Six on Wednesday.

Her manner of death was determined to be natural. The New York City Office of Chief Medical Examiner told People, "the amended determination was made following review of toxicology testing results." They added, "toxicology testing can be done without autopsy."

Leighton Meester as Blair Waldorf and Michelle Trachtenberg as Georgina Sparks on Gossip Girl. Image: The CW.

Trachtenberg got her start in commercials before scoring roles on Nickelodeon's The Adventures of Pete & Pete and on All My Children.

Her breaking role came in 1996 when she landed the titular character in Harriet the Spy. Trachtenberg went on to star in movies such as EuroTrip (2004) and Ice Princess (2005), as well as supporting roles in Mysterious Skin (2004) and Black Christmas (2006).

Throughout her career, Trachtenberg also appeared in other notable projects, including 17 Again (2009), Mercy (2009–2010), and television films like Killing Kennedy (2013) and Sister Cities (2015). She also ventured into production, executive producing series such as Guidance (2015–2017) and Meet, Marry, Murder (2021).

Michelle in 2006. Image: Getty.

Her last credited role was in 2023, when she graced our screens as Georgina Sparks once again on Max's Gossip Girl reboot.

Trachtenberg's Buffy co-star James Marsters, who played punk vampire Spike, paid tribute to the actor as a "beautiful soul".

He remembered her as "fiercely intelligent, howlingly funny, and a very talented person", saying would be dearly missed.

"She died much too young, and leaves behind scores of people who knew and loved her," he told TMZ.

Sarah Michelle Gellar, who she also costarred on Buffy with, wrote a tribute online saying, "Michelle, listen to me. Listen. I love you. I will always love you.

"The hardest thing in this world, is to live in it. I will be brave. I will live… for you."

"My heart goes out to her family who are good people, and are suffering the greatest loss anyone could bear. I hope everyone can give them space to heal in this most difficult time.

"Godspeed Michelle. You are missed."

Trachtenberg's ex-boyfriend, X-Men star Shawn Rashmore shared a touching tribute to the actor, saying her death was an "incredible loss".

"She was an incredible person and I will always remember the years we spent together fondly," he wrote on Instagram. "She was loving, quirky and would never pass up a law and order SVU marathon."

Gossip Girl co-star Ed Westwick said it was "so sad" to hear of her death. Meanwhile, Sex and the City's Kim Cattrall, who starred as Trachtenberg's coach in Ice Princess, shared her condolences.

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A post shared by Kim Cattrall (@kimcattrall)

Trachtenberg's final Instagram post was just days before her death.

Our thoughts are with her family and friends.

Feature image: Getty.