In addition, administration of olanzapine and other atypical APDs has been shown to increase blood levels of leptin and ghrelin, suggesting that leptin and ghrelin could also be a link between APD-induced obesity and diabetes (Jin et al., 2008; Albaugh et al., 2011b; Zhang Q. et al., 2013). Here, GHRL is linked to obesity due to melanocortin 4 receptor deficiency.