What Drives Influenza Vaccination in People with Diabetes? Evidence from the National Health Surveys of 2020 and 2023 in Spain

Background/Objectives: Diabetes is associated with an increased risk of influenza-related complications; therefore, annual vaccination constitutes an essential preventive measure. The objective of this study is to analyze the evolution of influenza vaccination coverage among the population with diabetes in Spain between 2020 and 2023 and to identify factors associated with adherence, comparing it with a matched population without diabetes. Methods: A cross-sectional study was conducted using data from the European Health Survey in Spain 2020 and the Spanish National Health Survey 2023, applying 1:1 matching by age, gender, and place of residence. Multivariable logistic regression was applied to assess time trend and to identify adherence predictors. Results: Vaccination coverage among individuals with diabetes increased from 52.0% in 2020 to 65.9% in 2023 and was higher than that observed among the matched participants without diabetes in both periods. Older age and the presence of comorbidities, such as myocardial infarction or respiratory diseases, were associated with a higher likelihood of vaccination, whereas alcohol consumption and smoking were associated with lower adherence among subjects with diabetes. The year 2023 was independently associated with a higher probability of vaccination compared with 2020 (OR: 1.82; 95% CI: 1.56–2.12). Conclusions: Although influenza vaccination coverage among the Spanish people with diabetes has improved following the COVID-19 pandemic, it remains below recommended targets, highlighting the need to strengthen targeted strategies aimed at less adherent subgroups.