[Atypical antipsychotic-associated impaired glucose tolerance]

Some reports of impaired glucose tolerance associated with olanzapine (OLZ) treatment have been published before OLZ was marketed in Japan. In Japan, we have been prohibited from using OLZ for patients with diabetes mellitus, since several cases with OLZ-associated impaired glucose tolerance including two deaths from diabetic coma have been reported. Here, we report four cases of OLZ-associated impaired glucose tolerance and review the points to consider in treatment with OLZ. Of our four cases, three cases were new-onset (non diabetes mellitus cases) and the other case was a diabetes mellitus-existent (diabetes mellitus case). In the non DM cases, the time to the onset of impaired glucose tolerance after initiating treatment with OLZ was 8-9 months, and the impaired glucose tolerance immediately improved after discontinuing treatment with OLZ and initiating treatment for diabetes mellitus. Therefore, it is necessary to continue long-term monitoring of the parameters of glucose metabolism for all patients treated with OLZ. Should impaired glucose tolerance develop during treatment with OLZ, treatment with OLZ should be discontinued immediately and treatment for diabetes mellitus should be started if necessary. Although the condition of diabetes mellitus was stable befor initiating treatment with OLZ in the DM case, hyperglycemia developed immediately after initiating treatment with OLZ and the condition remained unstable even after early treatment for diabetes mellitus. Therefore, it is necessary to check for a previous history of diabetes mellitus and hyperglycemia befor initiating treatment with OLZ. Correlations between weight gain and occurrence of impaired glucose tolerance are not clear, so it is necessary to monitor the occurrence of impaired glucose tolerance even in cases without weight gain.