^^ Don't worry too much about that. My levels didn't change at all during my pg. In actual fact they stayed consistent even though I was being told constantly that it was going to be harder to manage as I went further along in my pg.
One of the ladies in my bb group (on here) has GD and she seems to have sorted out her levels and she is 35 weeks now.
It really is trial and error with foods though. Some things would set me off and others that I thought would (like hot chips) wouldn't. If Special K is giving you grief, I'd not eat it or weigh it out each day to make sure it is the Special K that is playing around with your levels. (ie: measure out 1 cup) I found sometimes that even eating the same b'fast each morning my levels could be hampered by what I ate the night before, even though my night levels were fine.