Abstract
Background Diabetes mellitus is an important risk factor for dementia, Alzheimer's disease, and other neurodegenerative diseases. Recent findings have made the relationship between the inhibition of the dipeptidyl peptidase-4 (DPP-4) enzyme and cognitive functions an important research topic. Objective This study aimed to evaluate the association between DPP-4 inhibitor use and cognitive functions, serum brain-derived neurotrophic factor (BDNF), and pentraxin-3 (PTX-3) levels in patients with type 2 diabetes, compared with the patients who only use metformin treatment. Design, patients, and methods A total of 50 patients with type 2 diabetes (hemoglobin A1c levels at ≤%7.5) who were under treatment with metformin±DPP-4 inhibitor (n=25) or only metformin (n=25) were included in this cross-sectional study. Serum BDNF and PTX-3 levels were assessed using an enzyme-linked immunosorbent assay. A standardized mini-mental test (sMMSE) was used to evaluate cognitive functions. Results There were no significant differences in the characteristics of the study groups. The mean sMMSE score of the patients receiving DPP-4±metformin treatment was statistically higher when compared with patients receiving only metformin treatment (27.16±1.95 vs. 25.40±3.07; p=0.041). The BDNF levels of the patients receiving DPP-4±metformin treatment were considerably higher than the patients receiving only metformin treatment (394.51±205.66 ng/ml vs. 180.63±297.94 ng/ml; p=0.001). The difference in PTX-3 levels between study groups was not statistically significant (5.47±3.44 vs. 3.79±2.53; p=0.055). Conclusion When compared to metformin alone, the use of DPP-4 inhibitors in the treatment of patients with type 2 diabetes was associated with increased serum BDNF levels and improved cognitive functions.