As one who believes strongly in the value of natural treatments, I'd like to add a few comments:
1) CDP Choline - over at PDPower both myself and Juanhch both teste this one and came to the same conclusion. A little is good but a little more is a problem. In the latter case it tips your system over into producing acetyl-choline which is the opposing neurotransmitter to dopamine. When that happens, one is very unhappy.

2) Mucuna - Good but messy. Really does the job, but too much is, indeed, too much. Avoid the high end extracts since they are "too good."

I would add to the above list turmeric. It has long been a favorite and recently became more so when it was found that it balanced the HPA axis that is out of whack in, among other things, PD. This lowers cortisol which is one of the factors in the blood sugar problems being discussed. Add in antioxidant properties, anticancer, and the ability to dissolve the amyloid plaques of Alzheimer's and you have a respectable tool.