Associations of NLR, MLR, and (neutrophil + monocyte)/lymphocyte ratio with 30-day mortality in diabetic ICU patients with heart failure: A retrospective cohort study

Background Heart failure (HF) is a common complication in diabetes mellitus (DM), affecting approximately 40% of HF patients. While inflammation plays a crucial role in both conditions, the prognostic value of inflammatory markers in patients with both DM and HF remains unestablished. Objective To examine the associations of neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and (neutrophil + monocyte)/lymphocyte ratio (NMLR) with 30-day mortality in ICU patients with both DM and HF. Methods This retrospective cohort study analyzed 1318 patients with both HF and DM from the MIMIC-IV database. NLR, MLR, and NMLR were calculated from complete blood counts within 24 h of ICU admission. Multivariate Cox regression, restricted cubic spline analysis, and ROC curves assessed predictive performance. Results Among 1318 patients, 239 died within 30 days. The deceased group had significantly higher median values of NLR (10.9 vs. 6.5), MLR (0.9 vs. 0.4), and NMLR (12.1 vs. 7.0) compared to survivors (all P < 0.001). After adjustment, each one-unit increase in MLR was associated with 11% increased mortality risk (HR = 1.11, 95% CI: 1.04–1.19, P = 0.002), while NMLR and NLR showed 1% increases, respectively (NMLR: HR = 1.01, 95% CI: 1–1.01; NLR: HR = 1.01, 95% CI: 1–1.01; both P < 0.001). MLR demonstrated the highest discriminative capacity (AUC = 0.672), followed by NMLR (AUC = 0.658) and NLR (AUC = 0.650). Conclusion NLR, MLR, and NMLR are independent predictors of 30-day mortality in ICU patients with DM and HF, with MLR showing superior discriminative capacity.