Yes, there are some risks. First of all, your baby could grow to be quite large and there is no way you could deliver vaginally. Secondly, your baby could become hypoglycemic as soon as the baby is detached from you, which will require medication. Not to mention that you could also have problems if you did not treat your gestational diabetes. I would suggest getting that 3 hour test as soon as possible to see if you are at risk.
I am now also doing weekly non-stress tests because of the GD to make sure that the baby is progressing correctly.