APOE and diabetes mellitus: However, only two studies have examined the association between ApoE and obesity in schizophrenic patients, one of which shows that the APOE expression in the hippocampus of schizophrenic patients is significantly higher than that in the control group16, while the other showed that APOE gene could influence the prevalence of diabetes and possibly overweight in psychiatric patients17, and the mechanism may involve lipid metabolisms13.