The sympathoadrenal system plays an important role in the regulation of metabolic and cardiovascular activity. With respect to carbohydrate metabolism, specifically, catecholamines affect both insulin secretion and insulin action. Alterations in sympathoadrenal system function have been suggested to contribute to the constellation of disorders referred to as syndrome X (obesity, hypertension, NIDDM, and dyslipoproteinemia). The origin of any such abnormalities in sympathoadrenal function is unknown. The sympathoadrenal system, like other parts of the mammalian nervous system, is susceptible to environmental influences during development. Although these neurological alterations in rats are particularly prominent during the postpartum period, they are also apparent during intrauterine life. Moreover, the effects of these early environmental factors last well into adulthood and may represent permanent alterations in sympathetic nervous system behavior. Although the impact of maternal diabetes on sympathetic neural development has not been examined extensively, limited data available indicate that maternal diabetes may affect sympathetic nervous system development in the offspring. Although the full impact of maternal diabetes on neurological development in the offspring is unknown, given the myriad effects of the sympathoadrenal system on mammalian physiology, lasting changes in autonomic nervous system function may have potentially profound consequences for metabolic and cardiovascular regulation in adulthood.