An interesting report today on the finding that insulin and dopamine are intertwined in the brain at
http://www.sciencedaily.com/releases...1017090131.htm
Insulin is one of those things relegated to endocrinology as is cortisol and so on (i.e. hormones). These links hint at why stress and blood sugar levels mess with us so badly in the short term and may even be causal in the long term.
This also highlights the problem of thinking of PD as simply a neurological disorder. Until we bring in the endos (and immunos) to sit with the neuros at the table, we aren't going to see the big picture.