Diabetes, Vol 42, Issue 4 550-555, Copyright © 1993 by American Diabetes Association
Loss of potentiating effect of hypoglycemia on the glucagon response to hyperaminoacidemia in IDDM
S Caprio, WV Tamborlane, K Zych, K Gerow and RS Sherwin
Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06510.
IDDM subjects lose the ability to release glucagon during hypoglycemia.
Because replacement of basal levels of amino acids enhances the glucagon
response to hypoglycemia in healthy subjects, we tested whether raising
amino acid levels during hypoglycemia could reverse the defective
alpha-cell response in IDDM patients. For this purpose, 11 IDDM patients
(HbA1 9.4 +/- 0.6%) and 8 healthy, nondiabetic subjects received two
hypoglycemic insulin clamp studies (0.8 mU.kg-1 x min-1) in which plasma
glucose was clamped at 55 mg/dl (3.08 mM) for 180 min. During one of the
studies, an infusion of amino acids was superimposed between 120 and 180
min (0.3 g.kg-1 x h-1). This dose of amino acids had a small effect on
plasma glucagon levels during euglycemic hyperinsulinemia that was
comparable in normal and IDDM subjects. In healthy control subjects, plasma
glucagon rose by 80% during the initial hypoglycemic phase of the study.
The addition of amino acids produced a further sharp (200-250 ng/L, P <
0.02) rise in plasma glucagon, such a change did not occur in the absence
of amino acids. In contrast, plasma glucagon in IDDM patients failed to
increase during hypoglycemia alone and rose by only 40-50 ng/L (P < 0.05
vs. controls) when amino acid infusion was superimposed, even though plasma
amino acid levels rose to the same extent in IDDM and control subjects.
More importantly, the rise in glucagon produced by amino acids was
comparable during hypoglycemic and euglycemic hyperinsulinemia in the IDDM
patients, results strikingly different from those observed in nondiabetic
control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)