IL6 and Parkinson disease: Although we did not demonstrate an association between inflammatory factors and motor and non-motor symptoms in patients with PD, our findings revealed positive correlations between TNF-α and PD duration, IL-1β and PDQ-39 score, and IL-10 and HAMD score and negative correlations between IL-6 and UPDRS III score and IFN-γ and SCOPA-AUT score in patients with PD–T2DM.