Background: Metabolic acidosis is a frequent acid–base abnormality in critically ill patients and may reflect sepsis, shock, diabetic ketoacidosis, renal dysfunction, or other severe systemic disorders. Its severity and persistence may influence the need for organ support and ICU outcomes.

Aim: To assess the clinical profile of metabolic acidosis in critically ill patients admitted to the intensive care unit and to evaluate its association with treatment outcomes.

Methods: A prospective observational study was conducted in the Medical Intensive Care Unit of the National Institute of Medical Sciences & Research Hospital, Jaipur, from July 2024 to December 2025. Adults (>18 years) with metabolic acidosis identified within the first 24 hours of ICU admission were enrolled. Metabolic acidosis was assessed using arterial blood gas parameters, bicarbonate, anion gap and lactate. Disease severity, organ-support requirements, treatment modalities and ICU outcomes were recorded. Statistical analysis was performed using SPSS and Microsoft Excel.

Results: Seventy-seven patients were included. Mean age was 47.48 ± 16.90 years (range, 19–84 years), and 42 (54.5%) were male. Sepsis was the most frequent underlying diagnosis (18/77, 23.4%), followed by diabetic ketoacidosis (12/77, 15.6%), chronic kidney disease (10/77, 13.0%) and acute kidney injury (9/77, 11.7%). High anion gap metabolic acidosis predominated (49/77, 63.6%). Mean pH was 7.23 ± 0.07, bicarbonate 13.16 ± 3.18 mmol/L, PaCO₂ 30.8 ± 5.9 mmHg, base excess −10.5 ± 4.1 mmol/L, lactate 5.19 ± 1.87 mmol/L and anion gap 18.10 ± 5.07 mmol/L. Mean APACHE II score was 20.70 ± 9.09 and mean ICU stay was 8.83 ± 3.14 days. Mechanical ventilation was required in 32 (41.6%), inotropic support in 42 (54.5%) and renal replacement therapy in 34 (44.2%) patients. Overall, 43 (55.8%) recovered and 34 (44.2%) expired. Ventilatory support was significantly associated with outcome (p = 0.017), whereas inotropic support (p = 0.962) and renal replacement therapy (p = 0.284) were not. Conclusion: In this single-center cohort, metabolic acidosis was associated with substantial ICU mortality and a high burden of organ-support requirements. High anion gap acidosis was predominant, with sepsis being the most common underlying diagnosis. Early recognition, serial acid–base assessment and prompt treatment of the underlying cause remain central to ICU management. Larger multicenter studies are needed to determine independent prognostic factors and the impact of specific treatment strategies.