Be sure to talk to your doctor about changes to diet, exercise weight, target blood glucose levels, and drug treatment.
Diet: Instead of simply eating "more" when pregnant, eat a wider range of foods for nutritive benefits, including plenty of vegetables and fruits, nonfat dairy products, lean meats, fish, and whole grain.
Exercise: Incorporate low-impact exercise into your schedule, like walking, aerobics, swimming, or water aerobics. Avoid contact sports or high-impact activities like running and horseback riding.
Weight: If you start pregnancy at a normal weight, expect to gain 25-35 pounds. If overweight, gain 15-25 pounds. If obese, expect to gain 11-20 pounds.
Target blood glucose: Recommended levels by the American Diabetic Association are 60-99 mg/dl before eating, 100-129 mg/dl 1-2 hours after eating, and <6% A1C.
Treatment: Insulin is the treatment of choice for diabetics when pregnant, because it doesn't pass through the placenta to the baby. Few diabetes drugs are tested for use during pregnancy, so expect to be switched to insulin.