TFAM and diabetes mellitus: Understanding that despite the association of high-fat diet-induced diabetes with significant loss of DA neurons in toxin-induced in vivo PD models [30,31], these toxin-induced PD models cannot recapitulate the slow, progressive degeneration of DA neurons; therefore, we also used the transgenic MitoPark mice PD models which harbor homozygous disruption of the mitochondrial transcription factor A (Tfam) in the DA neurons and recapitulate the mitochondrial dysfunction in adult-onset sporadic PD, to determine the role of diabetes in PD.