SNCA and type 2 diabetes mellitus: Similarly, pathways of T2DM may influence the development of PD such as metabolic inflammation [31], downregulation of dopamine in the nigrostriatal pathway [32–34], long-term hyperglycemia [35], decrease in the expression of PGC-1α (peroxisome proliferator-activated receptor-gamma coactivator-1α) [36–39], increase in the expression of PED/PEA-15 (phosphoprotein enriched in diabetes/phosphoprotein enriched in astrocytes 15 protein) [40], increased methylglyoxal levels [41, 42], and the formation of alpha-synuclein amyloid fibrils [17].