The prevalence of diabetes mellitus is increased in relatives of patients with a non-affective psychotic disorder.

Patients with schizophrenia are more likely to develop diabetes mellitus (DM) compared to the general population. In relatives, however, an increased rate of DM has not consistently been reported. In this study, we compared DM rates in 1740 unaffected first- and second-/third-degree relatives of patients with a non-affective psychotic disorder to 1271 control subjects, by administering the Family Interview for Genetic Studies (FIGS). The prevalence of DM (6.1%) was increased in the relatives of patients as compared to the relatives of the healthy subjects (3.6%, OR=1.6, p=0.007). Our findings support the hypothesis of a familial, possibly genetic, link between DM and non-affective psychotic disorders.