Imidazole dipeptides such as carnosine (β-alanyl-l-histidine) and anserine (β-alanyl-N-π-methyl-l-histidine) are naturally occurring dipeptides present at high concentrations in the muscles and the brain in vertebrates. In addition to various functions proposed so far, central and peripheral administration of carnosine have been shown to regulate blood-glucose levels of rats with hyperglycemia induced by 2-deoxy-d-glucose. This effect was likely to be due to regulation of insulin and glucagon secretions by the autonomic nervous system. Carnosine also induces changes in physiological events that are regulated by the autonomic nervous system, e.g. lipolysis and thermogenesis in the white and brown adipose tissues, respectively. The autonomic nervous system is under the control of specific regions in the hypothalamus and the brain stem. The carnosine action on the autonomic nerves is suggested to involve histaminergic neurons located in the tuberomammillary nucleus and the master circadian clock in the suprachiasmatic nucleus of the hypothalamus. These findings indicate that carnosine regulates the blood glucose and other peripheral physiological events by affecting the central regulation of the autonomic nervous system.