Mitchell, a second-year pro, appeared in five games this season.
Glenn, also a cornerback, joined the Bears as an undrafted free agent after starring at Central Florida for two seasons. He started 25 games and had nine interceptions at Central Florida.
The Bears announced the moves Tuesday.
Chicago (4-5) has won two straight and four of six heading into Sunday's game against the Denver Broncos.
AP NFL website: www.pro32.ap.org and www.twitter.com/AP-NFL