hey... I have gone through a pregnancy without having GDM and with a very heavy diabetes burden in the family gene..guess its all luck to a large extent..
i was adviced by my doctor to avoid excessive eating and control the weight gain .. i was also asked to keep tabs of the calorie (especially carbs) intake during my pregnancy
go through this page for some basic info on this subject...
http://www.indianwomenshealth.com/Diabetes-In-Pregnancy-88.aspx
have fun.. enjoy the pregnancy.. be anxious but dont be worried.. if you know what i mean.. honey, worries will not chase away the chances of problems, in fact i understand that being worried is a sure way of inviting trouble.. continue light exercises (if your doc has asked you to) and maybe do some pranayam/yoga to sothe your nerves.. i used to listen to classical music at least 4-5 hours a day ... it helped..
have a great pregnancy.. let us know what happened