I had GD (probably) with DS (like you, failed the 1 hour, opted to skip the 3 hour, had some high fasting numbers but my meal numbers were very easily controlled even not following the diet very closely so not positive that I wouldn't have passed the 3 hour.) In any case, they considered that I had it and I ended up on oral meds for the fasting numbers because they never did get very good regardless of what we tried. DS was born healthy at 36+2 with no problems, after I had had severe pre-e and HELLP at 23 weeks with my first pregnancy.
So yeah, it does raise your risk, but it's not a guarantee. I think we've had some other posters here that had GD in subsequent pregnancies but did not get pre-e.
Me (29) DH (30)
#1-Olivia Caetlyn-9-28-09-9-28-09, 23+2 wks, emergency classic c-section, class I HELLP, IUGR
#2- Lucas Oliver (rainbow baby)- April 2011, 36+2 wks, HELLP and pre-e free! (lovenox and LDA pregnancy)
#3-Matthew, late October 2012...mostly normal, 37 wks, (lovenox and LDA again)
My blog: http://www.butterflies-and-rainbows.blogspot.com/