“…The glucose metabolism, low concentrations of exogenous insulin may increase cerebral glucose metabolism and then modulate selective brain functions such as memory [37]; 2. neuro-transmitter modulation, notably, low doses of insulin can reverse the anamnestic effects of cholinergic blockade [38]; moreover, in humans, rising plasma insulin levels increase CSF norepinephrine [39]. Besides, from our study emerges that the prevalence of DM in PD patients without dementia was similar to that of general population [21]; on the other side, the prevalence of "prediabetes" was strongly associated with dementia in our PD-D patients. Sixty-two percent of PD-D patients had IR of whom, following a 2 h-OGTT, the 30% had also IGT and 26% IR only.…”