AceShowbiz -

In a bid to promote her latest comedy "The Ugly Truth", Katherine Heigl visited "Late Show with David Letterman" on Monday, July 20 only to also talk about her show "Grey's Anatomy". The actress who portrays the terminally-ill Izzie on the ABC series spilled that the cast were back filming on July 15 and they must endure long working hours.

"Our first day back was Wednesday, and I keep saying because I hope it embarrasses them - a 17-hour day," Heigl told Letterman. "I think it's cruel and mean." She then continued describing how the first day of work was with her best friend T.R. Knight no longer there. "It was kind of great to be back. All my friends are there and at this point, they're sort of like family, but it was a little weird because T is not there anymore," she said.

Regarding what fate Izzie will take after flat-lining on the season 5 finale, Heigl won't give a definite answer. She said, "You last saw Izzie, you know, flat-lining. So, I won't give it away but, you know, I'm there so I'm either there as a ghost, on the other side or I survived a disease no one survives."

Heigl also managed to reveal that the show has two more years in contract but she has no clue on how long she will stick to it. "That's what I keep wondering," she answered with sarcasm.

The sixth season of "Grey's Anatomy" will be back on screen September 24, the same day "Flash Forward" will have its series premiere. Her big screen movie "The Ugly Truth" meanwhile, hits theaters on July 24.