Background <p>Incretin-based drugs, namely glucagon-like peptide 1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase 4 (DPP-4) inhibitors, may have neuroprotective effects. Thus, we assessed whether these drugs are associated with a decreased risk of dementia among patients with type 2 diabetes.</p> Methods <p>Using the Clinical Practice Research Datalink from the UK, we formed two new user cohorts of patients at least 50&#xa0;years of age with type 2 diabetes starting incretin-based drugs or sulfonylureas between 2007 and 2021. Hazard ratios (HRs) and 95% confidence intervals (CIs) for dementia were estimated separately for GLP-1 RAs and DPP-4 inhibitors using Cox proportional hazards models with propensity score fine-stratification weighting and inverse probability of censoring weights.</p> Results <p>Among 275,144 initiators of DPP-4 inhibitors or sulfonylureas, followed for 750,846 person-years, DPP-4 inhibitors were associated with a reduced dementia risk compared with sulfonylureas (4.4 vs. 5.7 events per 1000 person-years; HR 0.77, 95% CI 0.71–0.85). HRs decreased with increasing cumulative duration of use and dose. Similar associations were observed across dementia subtypes and individual DPP-4 inhibitors molecules. Among 181,215 initiators of GLP-1 RAs or sulfonylureas, followed for 530,415 person-years, GLP-1 RAs were associated with a similar reduction in dementia risk compared with sulfonylureas, although with high uncertainty (2.3 vs. 3.1 events per 1000 person-years; HR 0.74, 95% CI 0.46–1.18). The magnitude of the association increased with cumulative duration of use and dose but with high uncertainty.</p> Conclusions <p>In this population-based study, DPP-4 inhibitors, and possibly GLP-1 RAs, were associated with a reduced dementia risk compared with sulfonylureas.</p>