Importance of the gut–brain axis in the control of glucose homeostasis

Adult mammals finely match glucose production to glucose utilization, thus allowing glycaemia to be maintained in a physiological range of 0.8–1.2 mg/dl whatever the energetic status of the mammal (i.e. fed or fasted, rested or exercised). To accomplish this, peripheral signals originating from the gut ‘inform’ the central nervous system, which in turn is able to monitor the status of both peripheral glucose stores and ongoing fuel availability. Indeed, both secretion and action of hormones regulating endogenous glucose production and utilization are regulated by the autonomic nervous system. These gut signals are either hormonal (e.g. glucagon-like peptide-1, ghrelin and cholecystokinine) or neuronal (e.g. afferent vagus nerve fibres). Recent data, combined with the development of incretin analogues for treatment of diabetes, highlight the importance of the gut–brain axis, especially glucagon-like peptide-1 and ghrelin, in the control of glucose homeostasis.