The relationship between sympathetic nervous system activity and glucose and insulin metabolism is not fully understood. In the present study we therefore investigated the effect of raising arterial plasma epinephrine within the lower pathophysiological concentration range on insulin, glucose and phosphate in blood. Arterial plasma epinephrine was raised over 60 min by a stepwise increasing intravenous infusion in healthy men aged 20-40 years (n = 40). Compared with infusion of saline, epinephrine caused a small but significant rise in serum insulin of 10 +/- 26 pmol/L (p = 0.016), more than 70% increase in serum glucose (p < 0.0001) and a decrease in serum phosphate (p < 0.0001). The changes in serum insulin during epinephrine infusion correlated negatively with the changes in arterial plasma epinephrine (r = -0.46, p = 0.003) and the changes in serum phosphate correlated negatively with the changes in serum glucose (r = -0.42, p = 0.007). Thus, arterial plasma epinephrine raised within the lower pathophysiological concentration range over a rather short period of time (60 min) has pronounced effects on insulin, glucose and phosphate in blood. These results suggest that epinephrine when infused acutely may suppress the insulin response to raised glucose, and that the acute hypophosphatemic effect of epinephrine is related to the glucose production. Thus, when epinephrine is released into the circulation during various forms of daily stress, e.g. mental stress, it may significantly affect insulin and glucose metabolism.