I just accidently replied to a very old post on this subject.
I have never been diabetic, but I was having this problem last month (about 9 months out from RNY). My blood sugar fell to 47 and I almost passed out! My doctor told me to STOP carbs and focus on proteins, which sounded strange to me. He explained that when you eat carbs your body has to produce more glucose and then it has to fall down....or something like that.
Bottom line is that it worked for me. I will still have fruit occaisionally, but no pasta, bread, potatoes, crackers, etc. No more low blood sugar!