Not an expert but didn't want your thread to go unanswered - one of my friends had it in her first but not second pg.
She was monitored more closely for the first 28 weeks, then signed off.
As I say, I'm not an expert and haven't had GD myself but as I understand it from talking to my friend, you are more likely to get it 2nd time around than someone who's never had GD but it's definitely not inevitable.
There's a big support thread for those with GD, and some people have joined it expecting to get it because they had it in previous pregnancies, but have managed to escape it this time around, so having it once is certainly no guarantee of getting it again. Make sure you get tested around 16 weeks though, as this should be offered to women who've had it previously.
Thanks for all this - They didn't get round to detecting it until 30 weeks before and I had to inject myself with insulin - did you? I am dreading the GTTs - last thing i want to do and having to hang around the local hospital with a 17 month old!!