The West Ham boss was rushed into Whitechapel's Royal London Hospital suffering from chest pains following the Hammers' crucial 1-0 win against Middlesbrough yesterday.
The East London club have confirmed Roeder's complaint is not heart-related and that he is currently in a stable condition.
Roeder was a member of John and Glenn Hoddle's backroom team during their England days and the pair were good friends before and after that experience.
John said: "Glenn is a very close friend of mine and I was shocked, absolutely shocked when I heard the news.
"We were coming back on the team coach and as soon as we got home we got in touch with his family immediately. I spoke to his wife this morning to give our support.
"I'm very worried about him and I hope he will be alright. I would hate anything to happen to him. He is so dedicated and has worked so hard.
"People say he's got no passion - let me tell you he's got a lot of passion.
"He loves his club, his team and he loves his work.
"He's put in such a lot of work there that he's hardly got a family life. He has a beautiful family but he barely has the time to spend with them. I just hope it's not as serious as it could be.
"He's a young man as well and it all puts football in perspective."
John Gorman has sent out a heartfelt message of support for his friend and former England colleague Glenn Roeder.