Late Gestational Diabetes Onset/Diagnosis

So I passed the glucose test at 24 weeks, like 110. I was shocked and really excited because I had it with my first pregnancy (diet controlled) and assumed I would have it again, but after the negative test I thought I was in the clear....

Today I had my 34 week visit and I’m measuring big (she didn’t say how big) but she thinks he’s 6-7lbs already. She wanted me to start checking my blood sugar after meals and let them know if they’re high. Well, about an hour after a normal dinner I tested and came back at 163- she said be on the lookout for 130-140. Ugh.

So I haven’t been managing anything for ten weeks and am sooo bummed. And now a little terrified that I’ll be giving birth to a giant. I managed my GD so well last time and my first was still close to 9lbs, and she was born right at 40 weeks.

Anyone else get a late GD diagnosis?? Or at least have anything reassuring about birthing a 9+lb baby??