DOI: https://doi.org/10.36347/sjmcr.2026.v14i10.024

Pages: 2223-2225

Second-generation antipsychotics are associated with metabolic disturbances, of which diabetic ketoacidosis (DKA) is a rare but serious complication. Quetiapine, usually considered to carry an intermediate metabolic risk, has been associated with hyperglycemic emergencies in pharmacovigilance data. We report the case of a 21-year-old man with a normal body mass index (22.3 kg/m²) and no personal or family history of diabetes, who had been receiving quetiapine 100 mg/day for nine months without weight gain. He presented with a 48-hour history of abdominal pain, polyuria, polydipsia, and vomiting, with altered consciousness (Glasgow Coma Scale score of 14). Blood glucose was 6 g/L (33.3 mmol/L), ketonuria was 3+, and arterial blood gas analysis revealed severe metabolic acidosis (pH 6.92; bicarbonate < 3 mmol/L). Exudative tonsillitis was a possible precipitating factor. The patient improved with fluid resuscitation, continuous intravenous insulin, potassium replacement, and antibiotic therapy, and quetiapine was discontinued. The causality of quetiapine was rated as probable on the Naranjo scale. The absence of overweight and weight gain suggests that adiposity-independent mechanisms may be involved, although new-onset autoimmune type 1 diabetes could not be excluded without immunological testing. No glucose monitoring had been documented during nine months of treatment. This case highlights that severe DKA may reveal diabetes during quetiapine therapy and supports guideline-recommended glucose screening in all patients receiving second-generation antipsychotics, regardless of body weight.