Hyponatremia as a Predictor of In-Hospital Mortality in Diabetic vs. Non-Diabetic Heart Failure Patients

Abstract

Background: Hyponatremia is one of the most common electrolyte abnormalities observed in patients hospitalized with heart failure (HF) and is consistently associated with adverse clinical outcomes. Diabetes mellitus (DM), a frequent comorbidity in HF, may modify the prognostic impact of hyponatremia through mechanisms including renal dysfunction, neurohormonal activation, and osmotic shifts related to hyperglycemia. However, comparative evidence evaluating whether hyponatremia confers different mortality risk in diabetic versus non-diabetic HF patients remains limited. Objective: To evaluate the association between admission hyponatremia and in-hospital mortality among patients hospitalized with HF and to determine whether this association differs between diabetic and non-diabetic individuals. Methods: An analytical cross-sectional observational study was conducted among 150 adult patients admitted with confirmed HF to a tertiary care hospital. Serum sodium levels were measured at admission, and hyponatremia was defined as sodium <135 mmol/L. Patients were categorized based on diabetes status. Demographic, clinical, and laboratory data were collected from hospital records. Associations between hyponatremia and in-hospital mortality were analyzed using chi-square tests and multivariable logistic regression models adjusting for relevant clinical covariates. Results: The mean age of participants was 62.33 ± 13.15 years, and 60% were female. Hyponatremia was present in 86 patients (57.33%). Overall in-hospital mortality was 21.33%. Mortality was higher among patients with hyponatremia (26.7%) compared with those with norm natremia (14.1%). The highest mortality occurred among diabetic patients with hyponatremia (31.3%), followed by non-diabetic hyponatremic patients (21.1%). In multivariable analysis, hyponatremia remained independently associated with in-hospital mortality (adjusted OR 2.47; 95% CI 1.05–5.81). Conclusion: Admission hyponatremia is a significant predictor of in-hospital mortality in patients with HF, with a potentially greater adverse impact among those with diabetes mellitus. Routine assessment of serum sodium at admission may facilitate early risk stratification and guide targeted management in high-risk HF populations.