Glen missed the 2-1 win over Germany at Reading - whose Nathan Tyson scored both the goals - and Glenn Roeder explains:
"He would have played for England against Germany but Les Reed, who is the coach of the U20s and acting technical director of the FA, came to see me for a chat a couple of weeks ago.
"Les was really co-operative, saying that if he was around the first team, he would understand if he didn't make the game, but that if he wasn't, he would like to have him in the squad.
"Because he has started the last two games Les knew he wasn't going to be there."
Glen had no problems with the decision as he looks to make his first away start for the seniors, and Glenn adds:
"We have just got to keep working hard with him; he has started well in the two games and we have to accept he has a lot of inexperience.
"But it is very good that we managed to get him across to Millwall on loan to play first division football this year, and I am sure that is standing him in good stead.
"The important thing is we keep monitoring his progress and keep talking to, and working with, Glen - and it would be really wonderful if we could get him through all of these 12 games.
"But we must be ever mindful of the fact that he is onl 18, and not 19 until August, I think.
"He is a real young player, we mustn't get too carried away, and the media mustn't in their praise.
"We want to keep a lid on it because yoiung players must be allowed to develop away from the spotlight - not just Glen, but there are a few good teenagers across the country that come in, have a couple of good games, suddenly they are right in the spotlight and all sorts of predictions are made about them.
"It is not good for their development and we really have to learn in this country to try and keep the spotlight off young players.
"There is enough pressure on them anyway playing at this level without predictions that they are going to do this or they are going to do that.
"It does not happen in other big European countries where there is a much better understanding of football development - there is too much hype with our young players and they need to develop in their own time.
"We shouldn't be hearing adjectives about their performances before they are mature and experienced enough to handle it."