The link between atypical antipsychotic drugs and the development of diabetes has been hotly debated in the literature. In this review, we attempt to classify the various types of data published and presented in a hierarchical basis. Case reports and retrospective pharmacoepidemiological studies suggest that both conventional and atypical antipsychotic medications are associated with an increased risk of glucose abnormalities or diabetes. Prospective data examining the relationship between atypical antipsychotic drugs and diabetes began to emerge in 2003 and are much less conclusive. Estimates of the attributable risk associated with atypical antipsychotic drugs are low. The few studies that have included a placebo group suggest that we cannot necessarily blame antipsychotic medication when diabetes develops in an individual with schizophrenia.