AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 5 1266-R1272, Copyright © 1994 by American Physiological Society
Thermoregulatory responses to hyperinsulinemic hypoglycemia and euglycemia in humans
D. G. Maggs, A. R. Scott and I. A. MacDonald
Department of Physiology and Pharmacology, University of Nottingham, United Kingdom.
Hypoglycemia induces physiological changes that influence thermoregulatory
mechanisms. We studied such responses in a group of healthy males (mean age
23.5 yr, body mass index 23.7 kg/m2) during hyperinsulinemic euglycemia (E;
4.5 mmol/l) and hypoglycemia (H; 2.5 mmol/l) and under placebo control
conditions (P; saline). Plasma epinephrine (P < 0.0001) and
norepinephrine (P < 0.01) levels increased during H and were unchanged
during P and E. During H, early increases in metabolic rate (P < 0.05),
forearm blood flow (P < 0.01), and sweating (P < 0.01) were followed
by a fall in skin temperature (from -1.2 to -2.6 degrees C) and blood flow
(P < 0.01). Core temperature fell after 40 min of H and continued to
fall thereafter (-0.34 +/- 0.08 degrees C). E and P had minimal effect on
skin temperature and blood flow. In summary, in healthy human subjects, H
causes a fall in core temperature by heat dissipation at the skin surface
through evaporative heat loss and conduction of heat to the periphery,
despite an increase in metabolic heat production.
