Association of Inpatient Diabetes Specialist Consultation with Clinical Outcomes in Patients with Diabetes Hospitalized for Lower Respiratory Tract Infections: A Retrospective Cohort Study

Abstract

Background: Diabetes mellitus (DM) is associated with an increased susceptibility to lower respiratory tract infections (LRTIs) and more severe clinical courses, including prolonged hospitalization and increased mortality. During LRTI-related hospitalizations, clinical management often prioritizes the acute respiratory condition, potentially under-recognizing DM-related multimorbidity. We evaluated whether inpatient diabetes specialist consultation is associated with improved outcomes in this high-risk population. Methods: We conducted a retrospective cohort study of 677 adults with DM admitted for LRTI. Specialist consultation was defined as involvement of an endocrinology and/or diabetes nurse specialist during index hospitalization. Outcomes included length of hospital stay (LOHS) and 90-day mortality. Multivariable zero-truncated negative binomial regression (LOHS) and logistic regression (mortality) were adjusted for age, sex, Charlson Comorbidity Index (CCI), National Early Warning Score (NEWS), and pre-admission insulin use, hypoglycemic events, and admission laboratory parameters. Inverse probability of treatment weighting (IPTW) based on propensity scores was performed as a sensitivity analysis. Results: Among 677 patients, 84 (12.4%) received diabetes specialist consultation. Patients receiving consultation had lower unadjusted 90-day mortality (4.8% vs. 17.5%, p = 0.001) but longer median LOHS (9 vs. 7 days, p < 0.001). After multivariable adjustment, diabetes specialist consultation was associated with lower 90-day mortality (OR 0.23, 95% CI 0.08–0.68, p = 0.008) and longer LOHS (IRR 1.27, 95% CI 1.12–1.44, p < 0.001). The results were consistent in IPTW sensitivity analyses. Conclusions: In this retrospective cohort of patients with DM hospitalized for LRTIs, inpatient diabetes specialist consultation was associated with lower 90-day mortality, but longer hospital stay. These findings suggest that structured inpatient diabetes specialist involvement may contribute to improved medium-term outcomes in high-risk multimorbid patients. Prospective studies are required to determine causality and evaluate the impact of consultation timing and referral strategies.