Failed 1 hour GB Screening

I just found out I failed my gestational diabetes screening with a reading of 157. My clinics max is 129. Scheduled for the 3 hour test on Monday. I'm a vegetarian so I eat alot of carbs which I know I will need to scale back on. I've gained 30 pounds at 29 weeks. I'm looking for some words of wisdom from other screening failures, advice on the 3 hour test, and insight into what happens for the rest of the pregnancy and during labor if I do have GD. Thanks all.