Association between Plasma Levels of PAI-1, tPA/PAI-1 Molar Ratio, and Mild Cognitive Impairment in Chinese Patients with Type 2 Diabetes Mellitus

Background: Plasminogen activator inhibitor 1 (PAI-1) and tissue plasminogen activator (tPA) are involved in the complications of type 2 diabetes mellitus (T2DM) and early pathology of Alzheimer's disease. Objective: This study aimed to investigate the association between plasma PAI-1, tPA/PAI-1 molar ratio, and mild cognitive impairment (MCI) in Chinese T2DM patients. Methods: A total of 162 Chinese T2DM patients were recruited and divided into two groups according to the Montreal Cognitive Assessment score. Demographic data were collected, plasma PAI-1 and tPA levels were measured through enzyme-linked immunosorbent assay, tPA/PAI-1 molar ratio was calculated, and neuropsychological test results were examined. The association between PAI-1, tPA/PAI-1 molar ratio, and cognition was analyzed. Results: There were 66 diabetic MCI patients and 96 healthy cognition participants (controls). T2DM patients with MCI displayed significantly increased plasma PAI-1 levels (p = 0.016) and decreased tPA/PAI-1 molar ratio (p = 0.021) compared with the controls. High PAI-1 levels and low tPA/PAI-1 molar ratio were associated with MCI in T2DM patients, e.g., plasma level of PAI-1 were negatively correlated (r = -0.343, p = 0.007) with logic memory in T2DM patients with MCI. Linear regression analysis further revealed that PAI-1 concentration was an independent factor of diabetic MCI (p = 0.001). Conclusions: High PAI-1 levels and lowtPA/PAI-1 molar ratio were significantly correlated with T2DM-associated cognitive impairment, especially memory function, in Chinese patients.