David Letterman is relieved not to be hosting a late-night talk show anymore.

The 78-year-old star stepped away from the screen in 2015 and is grateful that he doesn't have a platform amid the current political turbulence in the US under President Donald Trump.

Asked if he missed his show on Jimmy Kimmel Live!, David said: "Boy you would think, but no - I'm so glad to be out from under this mess.

"People like you and people like Stephen (Colbert) and people like Seth (Meyers) do such a masterful job of defending this democracy. About all I'm capable of is showing up every now and then saying f*** Waymo and that's it."

Letterman had Trump as a guest on his show several times in the past but described the White House chief as a "fool" who should expect "ridicule".

He said: "Irrespective of party or political ideology - if the leader of the free world is a fool, the leader of the free world, then, should expect and examine every bit of ridicule he receives."

Letterman explained that he is grateful for the satire on shows such as Saturday Night Live as he lamented the "crippled" democracy of the US.

The presenter said: "Thank God for you, thank God for others, SNL and everybody else.

"It's just, I think it's the way things need to be in a democracy that's seemingly this crippled."

Meanwhile, David also told a humorous story about being mistaken for Mary Poppins icon Dick van Dyke.

He recalled: "A guy comes up to me, and he says, 'Excuse me, are you who I think you are?' And now, I'm all loaded up and I respond, 'Well, that depends on who you think I are.' That always gets a big laugh.

"He said, 'Dick van Dyke', and I said, 'No'."

Letterman quipped that he now has to wear a "name tag" so people know who he is.

The broadcaster said: "Here's what happens to me now: People used to know who I am, and now I have to wear a name tag to get anything going."