Caitlyn, previously known as Bruce Jenner, made her first public appearance on the cover of July's issue of Vanity Fair, which was unveiled yesterday.
Formerly known as Bruce Jenner, Caitlyn joined Twitter just moments after the magazine preview, and after four hours, had one million followers.
Tweeting from her new account, former Olympian Caitlyn, said: "Another Jenner world record, and at 65? Who'da thought! Humbled & honoured to have reached 1M followers in 4 hrs. Thank you for your support."
Caitlyn has now shattered President Barack Obama's Twitter record for reaching one million followers the fastest. Obama, who launched his @POTUS handle on 18 May, managed to rack up one million followers in under five hours.
Caitlyn had an outpouring of support from family and celebrities after the Vanity Fair cover was unveiled. In a chat with Buzz Bissinger for the magazine, she said: "If I was lying on my deathbed and I had kept this secret and never ever did anything about it, I would be lying there saying, 'You just blew your entire life. You never dealt with yourself,' and I don't want that to happen."
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