Janet always has good answers. I can only think of a few comments.
1) How much protein are you eating in a day? Can you give us an idea of what your daily menu looks like? High amounts of protein can definitely keep your blood sugar high.

2) Counter intuitive, but you may be getting *too much* exercise. It sounds like you have plenty just at work. I had a friend who broke a long stall by cutting way back on her daily exercise.

So please, give us some samples of what your daily eating looks like, and as Janet said - consider the timing of your meals, and definitely investigate Dr. Fung. I'm a huge Fung fangirl. Fasting seems to be helping me.