Olanzapine-Induced Diabetic Ketoacidosis: A Reversible Etiology Overlooked in Psychiatric Patients.

Background/Objective: Olanzapine is a second-generation antipsychotic medication with increased side effects of weight gain, hyperglycemia, and insulin resistance. Here we describe a case of diabetic ketoacidosis in a patient who started taking olanzapine 12 weeks before she presented. Case Report: A 73-year-old African-American female presented with a 1-week history of confusion, polyuria, and polydipsia. Her past medical history included type 2 diabetes mellitus, hyperlipidemia, and severe depression with psychotic features. Her medications were olanzapine 5 mg, duloxetine 90 mg, and rosuvastatin 5 mg daily. Three weeks prior, she was diagnosed with COVID-19 and treated for a urinary tract infection. Her physical exam upon admission included severely dry mucous membranes and labored respirations. The circulating glucose was 748 mg/dL (70-110), anion gap 39 mmol/L (7-16), and hemoglobin A1c (HgbA1c) 11.8% (105 mmol/mol). Three months prior, her HgbA1c was 6.7% (50 mmol/mol). She was treated with intravenous fluids and continuous insulin infusion followed by subcutaneous basal-bolus glargine and lispro after an anion gap of 13 mmol/L (7-16) was obtained. Two weeks into her hospitalization, olanzapine was discontinued. She was discharged on 10 units of glargine and metformin 500 mg twice daily. Five months after discharge, she indicated not taking any of the prescribed insulin or metformin. At this follow-up, her HgbA1c was 6.7%. Discussion: Olanzapine may impair insulin secretion by causing pancreatic beta-cell apoptosis. Conclusion: Increased awareness of the generalized metabolic effects and risk of diabetic ketoacidosis associated with antipsychotic medications is needed to develop a safe treatment plan for patients.