According to TV Line, the 'Born This Way' instalment will be lengthened because there is so much happening in the show.
The episode, which will feature a performance of the Lady GaGa track 'Born This Way', is expected to focus on the characters as they struggle with their self-image.
Rachel (Lea Michele) will consider having cosmetic surgery on her nose, while Lauren (Ashley Fink) will run for prom queen.
Meanwhile, Max Adler has previously suggested that the episode could involve a storyline for his character Karofsky and Cory Monteith claimed that it "gets kind of heavy".
Negotiations about extending the episode are thought to be ongoing, but if Fox agrees then producers are reportedly planning to shoot two more musical numbers to fill the time.
A spokesperson for Fox declined to comment.
Glee returns for a new episode in the US on April 19 on Fox and continues in the UK on Mondays at 9pm on E4.