BackgroundEmerging evidence suggests a role for orthostatic hypotension (OH) in contributing to the progression of Alzheimer disease (AD). The aim of the study was to investigate whether neural-derived plasma exosomal amyloid-β and tau protein levels are associated with OH in diabetes mellitus (DM) patients.MethodsThere were 274 subjects without dementia included in the study: 81 control participants (controls), 101 normotensive patients with DM without OH, and 92 patients with DM and neurogenic OH (DMOH). Neuronal-derived exosomal proteins were measured by ELISA kits for amyloid-β and tau.ResultsThe neuronal-derived exosome levels of Aβ42, T-tau, and P-T181-tau in the DM with OH group were higher than those in the DM and control groups. Multivariable linear regression analysis showed that the presence of OH in patients with DM was associated with elevated exosomal Aβ42 (β = 0.172, P = 0.018), T-tau(β = 0.159, P = 0.030), and P-T181-tau (β = 0.220, P = 0.003) levels after adjustment for age, sex, APOE ε4, duration of type 2 diabetes, HbA1c and cardiovascular risk factors. Furthermore, the levels of Aβ42, T-tau, and P-T181-tau in neuronal-derived exosomes were correlated with HIF-1α levels and the drop in mean cerebral blood flow velocity from the supine to upright position.ConclusionsThe presence of OH in DM patients was independently associated with elevated the Aβ42, T-tau, and PT181-tau levels in neural-derived plasma exosomes. Cerebral hypoperfusion from DM with OH are likely candidate mechanisms.Trial registrationChinese Clinical Trial Registry (Identifier: ChiCTR1900021544 ). Registered 27 February 2019.