The Irish star has missed the entire season so far after undergoing knee surgery and Glenn is concerned about the impact potential secondary injuries can cause.
"It's a slow recovery, we knew it would be quite slow," said Glenn. "He's on course but, with being out for that length of time, it's other injuries that cause the problems.
"Stephen Clemence was the same. He's recovered from his knee injury, but he's picked up a slight groin strain that's been holding him back. It was the same with Goran and it's always the problem when you've got long-term injuries.
"It's nothing alarming on the original injuries, it's life. If you're out three or four months, when you start training and go up a couple of gears there is obviously the chance of doing something else. That's the frustrating thing."
However, Glenn is hopeful that Steve will be storming up the right flank at some stage during the remainder of the season.
"We haven't a timescale for Stephen at the moment. We're hoping we'll get him back by the end of the season."
Glenn Hoddle says that there is no fixed timescale regarding a return date for flying full-back Stephen Carr.