Impaired glucose utilization in man during acute exposure to environmental heat

In 6 healthy males the oral glucose tolerance test (OGTT) was performed after the administration of 100 g glucose during the hyperthermic Finnish sauna bath (85 degrees C) of 30 min duration. The lowered insulin response (P less than 0.001) to glucose challenge during heating and the subsequent prolonged hyperglycemia (P less than 0.001) after heating were observed, when compared to OGTT under thermoneutral conditions (23 degrees C). It is suggested that the heat-induced decrease in visceral blood flow and stimulation of sympathoadrenomedullary and pituitary activity may be responsible for this effect.