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 2DM, 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 6months 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.