I control my diabetes with diet and exercise. Its taken me a few years to understand it all. I found it most helpful to keep a notebook, and write down everything, time, food, exercise, blood sugar, etc. That is how I worked out a regimine that works for me. What works for me, is to choose food/exercise combos that never let my blood sugar go above 120 (peak at ~1hour post meal) and be back under 100 by the 2 hour mark). On the bike I feel best in the 100-120 range.

I also found it very helpful to read the book Dr. Bernstein's Diabetes Solution. You also want to enlist the help of a good endrocinologist, especially one that supports diet/exercise control, with medication as a last (but sometimes necessary) resort, if that is what you seem to want.