Objective: To report a case of olanzapine-induced hyperglycemia leading to a hyperosmolar, hyperglycemic, nonketonic coma.
Case summary: A 51-year-old, 85.5-kg (ideal body weight 79.9 kg), white man presented to a Veterans Affairs hospital with a serum glucose concentration of 1596 mg/dL. Soon thereafter, he went into a hyperosmolar, hyperglycemic, nonketonic coma. Olanzapine therapy had been instituted less than six months prior to this event; approximately two months before this event, his blood glucose was 108 mg/dL. Eight days after stopping olanzapine, the glucose concentration returned to normal, and the patient no longer required insulin nor any other glucose-lowering agents.
Discussion: The insulin resistance caused by olanzapine is normally attributed to the weight gain associated with the drug. In this patient, it appears that olanzapine caused hyperglycemia by a mechanism other than weight gain.
Conclusions: This case report and others from the literature suggest that olanzapine therapy may induce hyperglycemia in some patients.