The Indianapolis Star and ESPN's Web site both reported Saturday that Glenn, 31, would retire and that he would likely not attend Colts training camp at the end of this month.
Indianapolis television station WISH reported Friday that Glenn has been telling teammates he's seriously considering retirement and than an announcement on his decision could come as early as next week.
Glenn told the station that he did not want to talk about the issue now.
The Associated Press left messages Saturday seeking comment with the Colts and Glenn's agent, Ralph Cindrich.
Cindrich told the Star that any response would have to come from Glenn, who has started 154 regular-season games during his 10-year career and appeared in the past three Pro Bowls.
Glenn, a former University of California standout, was the Colts' first-round draft choice in 1997. He anchored an offensive line that was one of the league's best last year, although it was sometimes overshadowed by quarterback Peyton Manning and his array of talented receivers and backs.
(Copyright 2007 by The Associated Press. All Rights Reserved.)