Furthermore, the liver-specific down-regulation of Sirt1 in these studies resulted in reduced hepatic fat synthesis and improved glucose homeostasis (Chen et al., 2008; Erion et al., 2009) – an effect that contradicts other studies showing increased hepatic FA and cholesterol, impaired glucose tolerance, hepatic inflammation and steatosis (Rodgers and Puigserver, 2007; Purushotham et al., 2009) upon Sirt1 deficiency. Here, SIRT1 is linked to Impaired glucose tolerance.