I had the exact same scenario with my 4th pregnancy...never had GD with the other three. I cried when they told me I was going to have to go on insulin, and felt so ANGRY with my body for not doing everything perfectly. My after meal numbers were ok, it was the morning number that was elevated.
But you know - I did what I needed to do, and gave myself those little insulin shots (way easier than I thought it would be), and kept monitoring my numbers. I gave birth naturally to a perfectly healthy baby boy, who weighed just a little less than babies 2 and 3.
This does mean that you are at a greater risk of developing type II diabetes later in life, so take this as your wake up call, and don't beat yourself up over it! Treat yourself with love and respect.
Oh, and don't let your doctors railroad you into a cesarean based on GD alone! Well managed GD is NOT dangerous to your baby.