The effects of sitagliptin, a DPP-4 inhibitor, on cognitive functions in elderly diabetic patients with or without Alzheimer's disease

Aims: The present study aimed to evaluate effect of sitagliptin, a dipeptidyl peptidase-4 inhibitor (DPP-4I), on cognitive functions in elderly diabetic patients with and without cognitive impairment. Methods: 253 elderly patients with type 2 DM, were enrolled in this prospective and observational study. After comprehensive geriatric assessment, the patients were divided into either sitagliptin or non-sitagliptin group. Results: A total of 205 patients who completed the study (52 with Alzheimer's Disease (AD)) were re-evaluated 6 months later. Sixth-month evaluation revealed no difference between sitagliptin and non-sitagliptin groups in terms of weight, body mass index, and HbA1c (p > 0.05). However, the number of patients that required reduced insulin dose was significantly higher in the sitagliptin group (p = 0.01). Sitagliptin therapy was associated with an increase in the Mini-Mental State Examination (MMSE) scores (p = 0.034); patients without AD receiving only sitagliptin or insulin showed higher MMSE scores as compared to the patients receiving metformin alone (p = 0.024). Likewise, the change in MMSE scores in AD patients receiving sitagliptin was significant and indicated improvement as compared to the patients receiving metformin (p = 0.047). Conclusion: Besides its effects similar to those of insulin and metformin in glycemic control and in reducing need for insulin, 6-month sitagliptin therapy may also associated with improvement of cognitive function in elderly diabetic patients with and without AD. Further randomized controlled trials are needed to support these results. (C) 2016 Elsevier Ireland Ltd. All rights reserved.