I had this for the last 3 pregnancies. I was slender, exercised daily, ate super healthy and slept 6-7 hours a night. It can happen to anyone. The not too funny thing is that your diet has to be really strict at a time when you want to chow down! And that the insulin injections a few times a day are no fun at all! It does go away as soon as the baby is born, but then you need to be aware that you are more likely to get diabetes later in life. I have my blood sugar tested once a year now. So far so good! Oh! The babies tend to be bigger too. It was a lot of work pushing 9 pounds out of a size 2 mama.