Characteristics and Care Practices in People Hospitalized for Heart Failure With Coexisting Diabetes: A Single-Center Retrospective Observational Study

Background: People hospitalized for heart failure (HF) often have coexisting diabetes mellitus (DM). However, the balance between HF- and DM-related inpatient care in specialized cardiovascular wards remains unclear. Objective: In this study, our aim was to compare HF- and DM-related inpatient care processes in people hospitalized for HF with coexisting DM and identify nurse-led opportunities for integrated management. Methods: This retrospective observational study was conducted in the specialized cardiovascular ward of a 400-bed Japanese hospital (April 2023–March 2024). Among 274 consecutive HF admissions, clinical characteristics were compared by DM status and, within the HF+DM subgroup (n = 79), HF versus DM care processes were assessed: specialist involvement, medication adjustments, and nursing documentation. Effect sizes (Cohen’s d , risk difference, and risk ratio RR) were calculated. Results: The prevalence of DM was 28.8%. Compared with people in the non-DM group, those in the HF+DM subgroup were younger (79.2 vs. 82.8 years; d = −0.31), had higher body mass index (23.5 vs. 20.9 kg/m 2 at discharge; d = 0.52), and lower left ventricular ejection fraction (40.3% vs. 47.0%; d = −0.44). In the HF+DM subgroup, HF care practices were more frequently documented compared with DM care practices: specialist nurse involvement 45.6% versus 3.8% (RR = 12.00), medication adjustment 89.9% versus 22.8% (RR = 3.94), and nursing documentation 53.2% versus 5.1% (RR = 10.43). Some process gaps exceeded 10-fold differences. Conclusions: Diabetes mellitus care was markedly under-addressed during HF admission. This is the first Japanese study to quantify HF–DM care disparities using effect sizes and highlight targets for nurse-led integrated pathways and stronger collaboration with endocrinologists.