In particular, preclinical work has shown a role of insulin on the brain dopamine system, especially in those areas related to the reward system (Figlewicz, 2003). In close agreement with this preclinical evidence, a recent clinical study showed a significant correlation between insulin level and alcohol craving in alcohol dependent patients (Leggio et al., 2008a). This study also showed a significant relationship between alcohol craving and the C-peptide, which is cleaved-off during the synthesis of insulin (Leggio et al., 2008a). Interestingly, other peptides involved in the modulation of glucose levels also correlate with alcohol craving and dependence, peptides such as ghrelin (Addolorato et al., 2006; Hillemacher et al., 2007), leptin (Kiefer et al., 2001; Hillemacher et al., 2007), thyroid hormones (Leggio et al., 2008b) and adiponectin (Hillemacher et al., 2009). Therefore, investigations aimed at examining the relationship between baseline blood glucose levels and alcohol use and craving during the course of treatment would help to elucidate the clinical implications of glucose levels in alcoholism.
