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

Her manner of death was determined to be natural.

Trachtenberg’s cause of death had initially been ruled “undetermined” after her family objected to an autopsy.

The actress was found dead in her New York City apartment on Feb. 26 after going into cardiac arrest. She was 39.

Sources previously told The Post that the “Buffy the Vampire Slayer” alum received a liver transplant within the last year.

Less than a week before she passed, Trachtenberg appeared to be “in very bad shape” while dining at Italian eatery Sartiano’s with friends, Page Six learned.

Trachtenberg reportedly looked “frail” and could hardly “walk down the stairs.”

The “Ice Princess” star sparked concerns about her health when she appeared gaunt in a photo shared via Instagram in January 2024.

At the time, fans expressed their worry in her comments section as Trachtenberg responded, “Explain to me how I look sick.”

“Did you lose a calendar and not realize I’m not 14. I’m 38. How sad for you to leave such a comment,” she wrote.

The former child star then shared another photo of herself, claiming she was “happy and healthy.”

“I’ve received several comments recently about my appearance. I have never had plastic surgery I am happy and healthy,” she captioned the snap. “Check yourself haters.”

While Trachtenberg never spoke publicly about her health, she “knew that death was a high possibility” of her condition, according to her pal Amanda de Cadenet.

“I am only sorry that the outcome was not a better one,” the photographer wrote in a tribute to the late star in February.

Blake Lively, Ed Westwick, Rosie O’Donnell and more celebs also mourned Trachtenberg.