Parkinson's Disease Support Group
Parkinson's disease is a movement disorder often characterized by muscle rigidity, tremor, a slowing of physical movement, and in extreme cases, a loss of physical movement. The primary symptoms of Parkinsons are due to excessive muscle contraction, normally caused by the insufficient formation and action of dopamine, which is produced in the dopaminergic neurons of the...
From the Michael J. Fox Foundation: "The most common sexual problem for men with Parkinson's disease is achieving and maintaining an erection, followed by impaired sexual arousal, drive, and orgasm."
From what I understand, if ED is diagnosed by a doctor a being related to a medical condition (in this case, Parkinson's), then insurance will generally cover it.