Diabetes, Vol 39, Issue 3 376-382, Copyright © 1990 by American Diabetes Association
Effect of plasma amino acid replacement on glucagon and substrate responses to insulin-induced hypoglycemia in humans
KS Nair, SL Welle and J Tito
Department of Medicine, College of Medicine, University of Vermont, Burlington 05405.
A defective glucagon response impairs glucose recovery from insulin-induced
hypoglycemia in some insulin-dependent (type I) diabetic patients. Our
objective was to determine whether the glucagon response to insulin-induced
hypoglycemia could be stimulated in nondiabetic humans. Because insulin
reduces plasma amino acid concentrations, and amino acids are known to
stimulate glucagon secretion, we investigated the effect of amino acid
replacement during insulin infusion on the glucagon response to
hypoglycemia in six healthy nondiabetic subjects. In two separate studies,
blood glucose was clamped at the postabsorptive level during a constant
infusion of insulin (0.05 U.kg-1.h-1) for 3 h. Blood glucose was then
reduced to 45 mg/dl over 20 min. Hormone and substrate concentrations
during recovery from hypoglycemia were monitored for 2 h. In the control
study, normal saline was infused, and in the other study, an amino acid
mixture was infused to prevent the insulin-induced fall in plasma amino
acids. Amino acid replacement did not change the basal glucagon levels but
resulted in a more robust glucagon response to hypoglycemia (from 184 +/-
24 to 292 +/- 36 pg/ml) than in the control study (from 176 +/- 30 to an
average 229 +/- 32 pg/ml, P less than 0.01). Plasma concentrations of
epinephrine, norepinephrine, cortisol, and growth hormones increased during
hypoglycemia, but the magnitude of the response was not different between
the control and amino acid-replacement studies.(ABSTRACT TRUNCATED AT 250
WORDS)