Glucose test in first trimester?

Melissa • I`m 37 and a mommy to a handsome little boy.
I just heard from my OB's nurse, and she told me my HbA1c level is on the high side so I need to have a first trimester glucose test to determine if I have pre-existing diabetes. Has this happened to anyone else? I mean I know I'm overweight, but diabetic?????? I've never been told I have diabetes nor does it run in my family. I'm almost 29 years old and my level was 5.6.  I'm kind of freaking out and am not sure what to think about this news.