Parkinson's and Diabetes Link
The reason behind this correlation is that high blood sugar is known to link with protein structures in a process called glycation. The bodily process of removing sugar connected to amino acids also creates advanced glycolytic enzymes (AGE’s) as a byproduct. AGE’s, in turn, are responsible for the production of a massive amount of free radicals. The damage associated with AGE’s — especially when they are based in the basal ganglia where the substantia nigra is located — manifests mostly in the creation of Lewy bodies which aggregate in the region due to oxidative stress within the neuronal tissue, interrupting neuronal activity, and promoting the destruction of the brain cells therein.