hopebewild, I'm not much of a fan of Dr McDougal but I have read Dr Neal Barnard's Diet for Reversing diabetes book. It is a higher carb diet focusing on whole grains, legumes, veggies, etc. The book shows those that went through the study were mostly able to show no signs of diabetes and those that did still have diabetes were able to control it. It seems since people with diabetes do well with either a low fat, higher carb diet or a higher fat, lower carb diet that maybe there is something about mixing fats and carbs that don't do well for diabetes.
You can't out-exercise poor eating habits.