Nationwide trends in dementia subtypes and in-hospital mortality among hospitalizations with type 2 diabetes in Spain, 2021–2024: A focus on sex disparities

Background The co-occurrence of type 2 diabetes mellitus (T2DM) and dementia represents a major public health challenge in Spain, where prevalence among hospitalized patients rose from 6.9% in 2011 to 10.6% in 2020. However, post-pandemic trends and sex-specific clinical outcomes remain under-characterized. We aimed to evaluate the frequency and temporal trends of dementia subtypes, clinical profiles, and predictors of in-hospital mortality (IHM) among T2DM-related hospitalizations in Spain (2021–2024). Methods We conducted a nationwide retrospective observational study using the Spanish National Hospital Discharge Database (RAE-CMBD) and analyzed 2,786,184 T2DM-related hospital discharge episodes recorded between 2021 and 2024. The unit of analysis was the hospitalization episode rather than the unique individual; therefore, recurrent admissions for the same person could be included as separate observations. Multivariable logistic regression identified independent predictors of dementia presence and IHM. Results All-cause dementia was coded in 180,623 hospital episodes, corresponding to 6.48% of T2DM-related hospitalizations. This proportion was higher among hospitalizations involving women than among those involving men. Regarding specific subtypes, AD was the most frequent diagnosis with 80,174 cases (2.88% prevalence), presenting an IHM of 16.3% across the study period. VaD affected 1.44% of the sample. A remarkably strong association was found between prior stroke/TIA and the presence of VaD (aOR 5.89; 95% CI 5.69–6.09). Hospitalizations involving all-cause dementia had higher in-hospital mortality (17.06% vs. 7.22%), lower ICU admission rates (1.33% vs. 7.58%), and higher frequencies of palliative-care coding (3.76% vs. 1.65%) than hospitalizations without dementia (Table 3). They also had shorter hospital stays and lower median estimated hospitalization costs (€6,129.3 vs. €8,602.94). A comprehensive breakdown of in-hospital mortality according to specific concomitant conditions and dementia status is available in S3 Table. Conclusions Among T2DM-related hospitalizations with dementia, female sex was associated with lower adjusted odds of in-hospital mortality. Prior stroke or transient ischemic attack was strongly associated with vascular dementia coding. Lower ICU admission and higher palliative-care coding were observed among hospitalizations involving dementia; however, the clinical reasons underlying these patterns cannot be determined from administrative discharge data.