The former England Under-21 and Wasps player did not earn a new contract after a two-year stint at Hughenden, and some great recent form.
"Leaving Glasgow is a huge blow because I have thoroughly enjoyed my time with the squad," said Joe. "I felt I had been performing pretty consistently since the home Heineken Cup clash with Toulouse - but at the end of the day there was no deal for me.
"I am not certain at this stage where my rugby future lies. There are one or two things in the pipeline, but nothing is set in stone. All I can say is that I am likely to be moving to somewhere in the British Isles."
Also being released is prop forward Andy Kelly who has been at Glasgow since the 2002-2003 season.