Tom Hanks revealed that he battles Type 2 diabetes during his Monday, Oct. 7, appearance on CBS' The Late Show with David Letterman.

Before promoting his new movie, Captain Phillips, the 57-year-old actor revealed his diagnosis.

"I went to the doctor and he said, 'You know those high blood sugar numbers you've been dealing with since you were 36? Well, you've graduated. You've got Type 2 diabetes, young man,'" Hanks said.

"My doctor said, 'Look, if you can weigh as much as you weighed in high school, you will essentially be completely healthy. You will not have Type 2 diabetes.' And then I said to her, 'Well, then, I'm gonna have Type 2 diabetes, because there is no way I can weigh as much as I did in high school...' I was 96 pounds."

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"You know, most of that was that big white afro that I wore back in the '70s," Hanks joked. 

"Something's going to kill us all, Dave," he told the late night talk show host.

The actor's frequent weight losses and gains may have contributed to his Type 2 diabetes diagnosis, according to CBS News' medical contributor Dr. Holly Phillips, who has not treated Hanks. He famously gained 30 pounds to play baseball coach Jimmy Dugan in 1992's A League of Their Own and for his role as Chuck Noland in 2000's Cast Away, he went from 225 pounds to 170 pounds to get into character as a man stranded on a deserted island.

"He'll have to watch what he eats very closely, he'll need to exercise regularly, but there's no reason he can't live a perfectly normal life," said Phillips. "In dramatic weight gain and dramatic weight loss, the equilibrium of the body is just completely off. So that might predispose him to developing type 2 Diabetes later."