Gestational Diabetes Help

I just turned 26 weeks and found out from my glucose test that I have gestational diabetes. My level was just slightly higher than normal. I am so clueless to this, this is my first baby after trying for a long time. What sort of things do I have to do? I feel bad I haven't been the best for eating great. I am getting referred to a diabetic clinic soon but in the meantime I don't know what to do.