Case Report: High-altitude exposure and severe respiratory infection precipitating diabetic ketoacidosis: new-onset ketosis-prone diabetes unmasked by physiological stress

Background Diabetic ketoacidosis (DKA) may represent the first presentation of previously unrecognized diabetes, with acute environmental and infectious stressors lowering the threshold for ketoacidosis. High-altitude hypoxia can impair glucose homeostasis and host defenses, potentially predisposing to severe respiratory infections. Case presentation A previously undiagnosed 28-year-old woman from sea level developed DKA 1 week after returning from a 5-day trip to Cusco, Peru (3,400 m). She presented with altered mental status, Kussmaul breathing, and severe metabolic acidosis (pH 7.09, glucose 548 mg/dL, bicarbonate 6.1 mmol/L, anion gap 26 mEq/L) in the setting of progressive respiratory symptoms and hypoxemia. Chest CT showed multifocal consolidations with cylindrical bronchiectasis and air trapping. Bronchoscopy with bronchoalveolar lavage revealed thick purulent secretions, and multiplex PCR identified parainfluenza virus, rhinovirus/enterovirus, Haemophilus influenzae , Staphylococcus aureus , Moraxella catarrhalis , and Candida albicans . Highly sensitive panels can detect colonization or shedding; therefore, results require syndrome-level correlation and stewardship-based interpretation. She required mechanical ventilation for 4 days. Standard DKA management and targeted antimicrobial therapy led to resolution of ketoacidosis within 48 h. Admission HbA1c was 9.0%, supporting antecedent chronic dysglycemia rather than isolated stress hyperglycemia. The combination of negative diabetes autoantibodies, preserved C-peptide (2.1 ng/mL), and subsequent insulin independence was most consistent with an A − β + ketosis-prone diabetes phenotype unmasked by acute stress. Pulmonary function and diffusing capacity fully recovered by 6 months. Conclusion This case highlights DKA precipitated by recent high-altitude exposure and severe polymicrobial pneumonia in the setting of previously unrecognized chronic dysglycemia, consistent with ketosis-prone diabetes. It underscores the diagnostic value of early bronchoscopy with molecular pathogen detection and the need for stewardship-based interpretation of multiplex PCR results in complex metabolic–respiratory presentations.