To my knowledge, this was the first study to explore the association between APOE E4 and obesity in elderly schizophrenic patients, and we found that (1) The prevalence of obesity in elderly patients with schizophrenia was 15.9%, and its risk factors included elevated fasting blood glucose, hypertension, and hyperlipidemia; (2) APOE E4 was associated with hyperlipidemia, but not was with hypertension or diabetes in elderly schizophrenic patients; (3) APOE E4 was not associated with hyperlipidemia, hypertension or diabetes in the normal elderly. This evidence concerns the gene APOE and diabetes mellitus.