Tight control of insulin action in liver is a crucial determinant for the regulation of energy homeostasis. Grb14 is a molecular adapter, highly expressed in liver, which binds to the activated insulin receptor (IR) and inhibits its tyrosine kinase activity. The physiological role of Grb14 in liver metabolism was unexplored. In this study we used RNA interference to investigate the consequences of Grb14 decrease on insulin-regulated intracellular signaling and on glucose and lipid metabolism in mouse primary cultured hepatocytes. In Grb14-depleted hepatocytes, insulin-induced phosphorylation of Akt, and of its substrates GSK3 and Foxo1, were increased. These effects on insulin signaling are in agreement with the selective inhibitory effect of Grb14 on the receptor kinase. However, the metabolic and genic effects of insulin were differentially regulated after Grb14 down-regulation. Indeed, the insulin-mediated inhibition of hepatic glucose production and gluconeogenic gene expression was slightly increased. Surprisingly, despite the improved Akt pathway, the induction by insulin of SREBP-1c maturation was totally blunted. As a result, in the absence of Grb14, glycogen synthesis as well as glycolytic and lipogenic gene expression were not responsive to the stimulatory effect of insulin. This study provides evidence that Grb14 exerts a dual role on the regulation by insulin of hepatic metabolism : it inhibits IR catalytic activity, and acts also at a more distal step, i.e. SREBP-1c maturation, which effect is predominant under short-term inhibition of Grb14 expression.