CBS has declined to comment on any special security measures being taken at Letterman's midtown Manhattan theater for the Monday taping.
Last week, a frequent contributor to a jihadist website posted a threat to Letterman. He urged Muslim followers to "cut the tongue" of the late-night host because of a joke the comic had made about al-Qaida leaders on his CBS show. The website is a popular Internet destination for radical Muslims.
It was unknown whether Letterman planned to address the threat on the air.
