Risk Factors for Mortality in Critically Ill Patients with Diabetes Admitted to the ICU: A Single-Center Retrospective Observational Study

<b>Background and Objectives</b>: Diabetes mellitus (DM) is a highly prevalent comorbidity among critically ill patients and may significantly influence intensive care unit (ICU) outcomes through metabolic, immune, and cardiovascular mechanisms. This study aimed to evaluate the impact of DM on clinical profile, comorbidities, complications, need for intensive support, and mortality in adult ICU patients. <b>Materials and Methods</b>: A retrospective observational study was conducted between January and December 2024 in a tertiary ICU, including 1344 adult patients. Among them, 435 (32.37%) had DM. Demographic data, admission diagnoses, laboratory parameters, comorbidities, complications, therapeutic interventions, and outcomes were analyzed. Comparative statistical analysis and multivariate logistic regression were performed to identify independent predictors of ICU mortality. <b>Results</b>: Patients with DM were significantly older than patients without diabetes mellitus (non-DM group) (69.62 ± 10.26 vs. 67.16 ± 14.26 years, <i>p</i> < 0.001) and more frequently female (57%, <i>p</i> = 0.0002). At admission, they presented higher glycemia (204.7 vs. 134.0 mg/dL, <i>p</i> < 0.00001), reduced glomerular filtration rate (47.2 vs. 59.5 mL/min/1.73 m², <i>p</i> < 0.00001), and more pronounced lymphocytopenia (<i>p</i> = 0.025). Cardiovascular and renal comorbidities were significantly more prevalent in DM, including hypertension (76.3%), heart failure (32.4%), and chronic kidney disease (33.1%) (all <i>p</i> < 0.01). DM was associated with increased odds of sepsis (OR 1.56), acute kidney injury (OR 1.51), and obesity (OR 2.57). ICU mortality was significantly higher in patients with DM (54.9% vs. 46.3%, <i>p</i> = 0.004; RR 1.19). Independent predictors of death included mechanical ventilation (OR 36.48), inotropic therapy (OR 4.74), hemodialysis (OR 2.57), elevated lactate, neutrophilia, and reduced glomerular filtration rate (GFR). <b>Conclusions</b>: DM was associated with increased ICU mortality and a higher burden of cardio-renal comorbidities and complications; however, mortality in the multivariate model was primarily driven by markers of organ dysfunction and the need for advanced supportive therapies. Early risk stratification and individualized management strategies are essential to improve outcomes in critically ill patients with diabetes.