This review summarizes many of the published reports about the production of melatonin and it’s role in regulation of carbohydrate metabolism, interrelationships between melatonin, insulin, glucagon and diurnal signaling the blood-glucose-regulating of the islet. The results of experimental and clinical investigations support that low melatonin levels and absence it’s circadian rhythm play the role in the development of gestational diabetes mellitus in womens with pathology of neuroimmunoendocrinology system and suggest the possibility of prognosis and prophylactic this complication of pregnancy.