Diabetes and psychosis: olanzapine may not be the culprit.

To the Editor—I read with interest “Olanzapine-induced diabetic ketoacidosis in a Chinese Man” by Wong et al published in the February 2007 issue.1 Although the patient did develop diabetic ketoacidosis while taking olanzapine and this association has been noticed previously with olanzapine as well as with other firstor second-generation antipsychotics, it is somewhat presumptuous to assume olanzapine was the cause. An association between diabetes and psychotic disorders was described long before the introduction of pharmacological agents for the treatment of schizophrenia and bipolar disorder. The most recent edition of the Canadian guidelines on risk factors and treatment of diabetes mellitus has included schizophrenia as a risk factor for diabetes mellitus and current literature finds the diabetes prevalence rate in people with schizophrenia is 2 to 4 times that of the general population and 2 to 3 times that of the general population in those with bipolar disorders.2,3