Metabolic effect of high environment temperature on non-diabetic and diabetic rats.

Blood lipids and glucose were studied in streptozotocin diabetic rats during hyperthermia. Blood glucose, free fatty acids (F.F.A.) and glycerol of diabetic rats with a rectal temperature of 42 degrees C (hyperthermic) were elevated significantly above those values found in normothermic (TR = 38 degrees C) diabetic or normothermic non-diabetic rats as well as hyperthermic non-diabetic rats. Streptozotocin diabetes caused an elevation in blood triglycerides of normothermic rats, but this hypertriglyceridemia was depressed in diabetic rats during hyperthermia. As in the case of diabetic animals, hyperthermia also caused a depression in the blood triglycerides of non-diabetic rats. However, unlike in the diabetic animals, the blood F.F.A. of non-diabetic rats were depressed during hyperthermia. Although hyperthermia caused a significant increase in the blood glucose of the diabetic animals, no significant change in blood glucose was shown in the hyperthermic non-diabetic rats. Blood cholesterol did not change significantly in the non-diabetic or diabetic animals during hyperthermia. The blood changes of these "energy substrates" are discussed with respect to their possible role in the extreme sensitivity of diabetics to high environmental temperature and "heat stress".