• clozapine;
  • olanzapine;
  • risperidone;
  • quetiapine;
  • type 2 diabetes;
  • antipsychotic drugs



To review studies conducted to evaluate the risk of type 2 diabetes in patients treated with different antipsychotic drugs (AP).


a MEDLINE search (January 1985–February 2003) was conducted to establish the potential relationship between the exposure to AP (conventional and second generation) and the development of type 2 diabetes. Studies were classified according to their experimental design as prospective and retrospective (incidence and prevalence based).


Twenty-one studies were selected: nine prospective and eleven retrospective.

Data Synthesis and Conclusions

Patients with schizophrenia treated with different AP have an increased risk of developing type 2 diabetes compared with the general population. The data so far available, however, do not establish whether the increasing risk of developing diabetes is a function of the schizophrenia itself or is induced by the antipsychotic treatment. A number of methodological flaws in the study design and data collection do not allow conclusions to be drawn on the risk between patients treated with conventional drugs versus those treated with new ones. Copyright © 2004 John Wiley & Sons, Ltd.