The differential effect of risperidone and olanzapine on insulin sensitivity after 3 weeks of treatment: a HOMA pilot study.

Background And Methods: Patients with an acute psychotic episode underwent HOMA testing for insulin sensitivity (IS) prior to and after 3 weeks of treatment with olanzapine (n = 7) or risperidone (n = 7).

Results And Discussion: The HOMA-IS index was reduced in the olanzapine group, but significantly increased in patients treated with risperidone. There was a significant "time × medication" interaction (p = 0.03). The BMI significantly increased as a result of both treatments. IS can be acutely ameliorated by antipsychotic treatment with risperidone despite weight increase.

Conclusions: Compared to risperidone, the IS is impaired after a 3-week treatment with olanzapine. Already short-term antipsychotic treatment may have eff ects on insulin sensitivity.