Breathe deeply and relax-- you and your baby should be fine if you get serious about taking care of yourself. You don't say what 'full-blown' means-- is it gestational diabetes, or true type-1? I will presume it's gestational. I have had a few close friends who had gestational diabetes; they followed the recommended diet, took care of themselves, and they and their babies were fine-- and the diabetes never returned. (All are normal weight/thin and exercise regularly, and their kids are now older teens.)
I am not a doctor, just the mom of a 17-year-old diabetic who desperately wants to have children someday, and I know that even women with long-established type-1 diabetes quite often have good pregnancies and healthy children. Just talk with your doctor about what you need to do, and do it, and you and your baby will be fine.
Take care and good luck.
I just thought I would give you some more words of encouragement. I am a mother of two, I have had diabetes for 26 years. My pregnancies were probably harder than most, but I did it. You just have to work closely with your doctor and as said above breath and try to calm down. I kept my blood sugars at good levels and I had two healthy children, both at normal weights and both are healthy children today. I would suggest reading as much as you can about gestational diabetes. Go to the American Diabetes Assoc. website. Ask your doctor for more information. See if you can go see a dietician to help you sort through your eating plan. And keep asking questions when you have them, on this site. I know the other volunteers and viewers will help you by answering questions that may come up! You can do this and you and your baby will be fine.
The good news is that you only have 3 more months to go. Just watch those sugar levels for three months, and your baby will be fine. Hopefully your diabetes will go away after the baby is born. Did your doctor tell you what causes gestational diabetes? Some of the hormones that are present in large amounts while you are pregnant act to make you insulin-resistant. So the cause of MOST gestational diabetes is the hormonal imbalance, and when this normalizes after the birst of your baby, hopefully the diabetes will go away. So hang in there and take good care of yourself.