Atypical antipsychotics and new onset diabetes mellitus. An overview of the literature.

During the last few years, several case reports and studies have been published on the potential diabetes mellitus (DM)-inducing effect of some atypical antipsychotics, especially clozapine and olanzapine. The purpose of our study was to evaluate diabetogenic effects of atypical antipsychotics in the literature. In order to give a full-scale overview, both peer-reviewed publications and oral and poster presentations on this subject were screened. We found 27 case reports of new-onset DM for clozapine, 39 for olanzapine, 4 for risperidone, and 3 for quetiapine. Related to the year of introduction of these drugs on the market and the number of treatment days of each drug during the last 6 years in 13 western countries, Brazil, and Japan, the cases show an over-representation of cases related to olanzapine and clozapine. In the majority of cases, risk factors (DM family history, obesity, Negroid ethnicity) were present. Eighty-four percent of the cases arose in patients < 50 years, in contrast to the general population (most cases, > 50 years). Comparative epidemiological studies point in the same direction, with two studies showing no differences between the atypical drugs. Antipsychotic agents are used often for treatment of schizophrenia, a condition that appears to be associated with DM also in untreated subjects. Some antipsychotics appear to induce new-onset diabetes mellitus. In view of the health risks of DM and the predisposition in patients with schizophrenia, it is advised to be cautious with prescription of antipsychotics that are associated with new-onset DM. Especially in predisposed patients (family history of DM, obese, Negroid ethnicity), reticence in this respect is required. Moreover, careful monitoring of weight, BMI, and glucose levels is advised both before these antipsychotics are prescribed and during treatment.