High-dose olanzapine-induced improvement of preexisting type 2 diabetes mellitus in schizophrenic patients

Objective: During the last few years there have been numerous publications concerning glucose dysregulation and antipsychotic treatment with new-onset diabetes and exacerbation of existing disease being reported. At the same time three anecdotal reports describing decrease of blood glucose level during clozapine and olanzapine treatment were published. Here we report two cases of clinically significant dose-related reductions in glucose levels in schizophrenic and schizoaffective patients suffering from pre-existing type 2 diabetes during high dose (40 mg/day) olanzapine treatment. To the best of our knowledge, this is a first report of decreasing glucose blood levels in association with olanzapine therapy in pre-existing type 2 diabetes. Antipsychotic treatment with high doses of olanzapine showed that the relationship between olanzapine and glucose regulation is more unambiguous than usually assumed. Conclusions: There is a need for further studies in order to define the influence of high dose olanzapine for schizophrenic and schizo-affective patients suffering from type 2 diabetes.