Recent reports suggested that the 'Born This Way' instalment is being lengthened because there is so much happening in the show.
Brennan has now told Digital Spy that news of the extra time is "great".
"We're always desperately cutting down our episodes," he said. "We're always throwing away stuff that I really love to get it down to time. It will be actually really interesting to have that extra whatever it will be - 24 minutes - added on."
Brennan claimed that the episode will be "fantastic" and explained that the longer running time will allow the producers to include some songs which would otherwise have been cut.
"I just think the story's going to be very 'on'," he said. "It's going to be a really Glee episode of Glee and the music, that song, is just going to fit in really well, I think. I think it will be one of those episodes that cracks away - sometimes the show can really do that, where you just feel like it's really cracking and funny and smart. I think that ['Born This Way'] will be one of those episodes."
Glee airs on Mondays at 9pm on E4 in the UK. The show returns with a new episode in the US on April 19 on Fox.
> Click here to read our interview with Ian Brennan