Please try not to worry. I've been totally stressed and an emotional wreck since my diagnosis but once you get your head around it it's really not that bad. Initially they'll want you to try and control your blood sugar levels by adjusting your diet and you'll be given a finger pricking kit to test yourself first thing in the morning and then an hour after each meal. It sounds a lot worse than it is. Don't get me wrong, you wouldn't love doing it, but you really do get used to doing it surprisingly quickly.
I've found it useful to keep a diary of everything I eat and then keep track of the subsequent reading so I can identify what foods trigger my levels.
You should be given a couple of weeks to try with the diet changes and if that doesn't work they would prescribe metformin tablets which help your body process the glucose more effectively. It's only in very extreme cases that they prescribe insulin for gestational diabetes as far as I'm aware.
I don't mean to sound or come across as a know it all but I've been doing A LOT of reading into it over the last fortnight. To be honest, the information I was given by the hospital dietician was next to useless and all the helpful stuff I've learnt has been from searching old threads on here. There's a lot of reassurance from other sufferers and, more helpfully, lots of tips about what foods to avoid and what foods have worked for other people.
It's taken me very nearly 7 days but my sugars are finally starting to stabilise and have all been below my target for the last few readings so if they stay like that I'll be keeping off the tablets for as long as possible, I don't want to take them unless I absolutely have to. It's been hard adjusting my diet but I keep telling myself that it's only for another 12 weeks at the most and my baby's health is worth the sacrifices.
I really hope what I've said has helped calm you a bit and that you don't have GD, but if you do look at old threads on here and don't hestitate to get in touch with me if I can help in any way. I really don't mind and I know all too well how scary it is and worrying (this if the first day I haven't broken down in tears for 2 weeks!!).