The Tigers went down 48-42 away to a Diamonds side that they were favourites to beat.
The Ashfield men went to Tyneside hoping to go some way towards replicating the huge 61-29 defeat inflicted on today's hosts by title rivals Poole just seven days ago.
But they never managed to get in front at any point in the meeting, and advantages to the home team in heats 13 and 14 ensured Newcastle could not be caught.
It gives Glasgow another point on the board, but Brown - whose side had exclusions on three occasions for touching the tapes - said: "It's the most disappointed I've been all season.
"There's no hiding it, it's a shocker. We really missed Ulrich Ostergaard again tonight, we were a bit ring rusty and the exclusions didn't help, but that's just excuses - at the end of the day, we weren't good enough.
"We didn't win enough races and that's what cost us. You don't win away from home winning that many races.
"Our guest Stevie Worrall did OK and Sam Jensen did very well on his first visit to Newcastle - I was pleased with him - but other than that, there's not much to be pleased about."
Glasgow remain top by a point to rivals Edinburgh after 14 meetings.
The Tigers next face a huge double header against Leicester - another of the favourites to win the SGB Championship - who are led by former Ashfield boss Stewart Dickson.
Brown said: "It's a big weekend and we have to pick ourselves up, because it's the biggest challenge we've had so far.
"Thankfully most of the team are racing during the week, which won't do them any harm, and those who aren't will get a bit of practice - so all seven of them will be on the bike at some point.
"But racing is something totally different to practice and it will be extremely difficult. Hopefully we can go out and surprise some people."