Glass was diagnosed with a concussion, Michelle Crechiolo of the Penguins' official site reports Sunday.
Glass (upper body) was put on injured reserve Friday, per the NHL media site.
Glass logged an assist and two hits in Thursday's 2-1 overtime win over the Ducks.
Glass (illness) is slated to return to action for Tuesday's game against the Wild, Penguins play-by-play announcer Josh Getzoff reports.
Glass recorded an assist, three shots on goal and a plus-2 rating in Sunday's 6-3 loss to the Jets.
Pittsburgh acquired Glass, a 2025 third-round pick and a 2026 sixth-round selection from Nashville on Tuesday in exchange for Jordan Frasca.
Glass scored three goals, including the game-winner, in Saturday's 5-1 victory over the Avalanche.
Glass scored a goal on two shots in the Predators' 5-2 loss to the Canucks on Tuesday.
Glass (upper body) was removed from injured reserve Saturday, making him available for the evening's game versus Toronto.
Glass (upper body) was placed on injured reserve Tuesday.