Demographic and Clinical Characteristics of Hospitalized Patients with Type 2 Diabetes Mellitus and Comorbid Parkinson's Disease in Spain: A Nationwide Observational Study (2017-2023).

Type 2 diabetes mellitus (T2DM) and Parkinson's disease (PD) are two highly prevalent chronic conditions that often coexist in older adults. Their interaction may influence clinical outcomes, particularly during external stressors such as the COVID-19 pandemic. This study aimed to assess the prevalence and temporal trends of PD among hospitalized patients with T2DM in Spain (2017-2023), evaluate sex-based differences in clinical characteristics and outcomes, examine the impact of the COVID-19 pandemic, and identify predictors of PD diagnosis and in-hospital mortality (IHM). We conducted a retrospective, nationwide study using the Spanish National Hospital Discharge Database (RAE-CMBD). Adults aged ≥40 years hospitalized with T2DM were included. PD cases were identified using ICD-10 codes. Joinpoint regression assessed temporal trends, and multivariable logistic regression identified factors associated with PD and IHM. Among 5.1 million T2DM-related hospitalizations, 107,931 (2.41%) involved PD. PD prevalence increased over time, particularly among women. Men accounted for most PD cases and were younger than their female counterparts. Depression and anxiety were more frequent in women and associated with PD in both sexes. IHM peaked at 14.6% in 2020, coinciding with the COVID-19 outbreak. Predictors of IHM included older age, higher comorbidity burden, dementia, and COVID-19 diagnosis. The coexistence of PD and T2DM in hospitalized patients is associated with clinical complexity and increased mortality. Personalized, multidisciplinary care is essential to address sex-specific patterns, psychiatric comorbidities, and vulnerability to systemic stressors.