Diabetes Care, Vol 16, Issue 8 1124-1130, Copyright © 1993 by American Diabetes Association
Glycemic actions of alanine and terbutaline in IDDM
BV Wiethop and PE Cryer
Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110.
OBJECTIVE--To test the hypothesis that the amino acid Ala and the beta
2-adrenergic agonist terbutaline raise plasma glucose concentrations
substantially, and do so through different mechanisms, in IDDM patients.
RESEARCH DESIGN AND METHODS--We administered these (Ala: 20 and 40 g,
orally; terbutaline: 2.5 and 5.0 mg orally and 0.25 mg subcutaneously) and
placebos in random sequence to 6 nondiabetic subjects and 6
insulin-infused, initially euglycemic IDDM patients, each studied on six
different occasions. Inhaled terbutaline, 0.4 mg, was also tested on a
seventh occasion in IDDM patients. RESULTS--Ala administration raised
plasma glucagon (P = 0.0219), C-peptide (P = 0.0014), and insulin (P =
0.0094), with no significant change in plasma glucose, in nondiabetic
subjects. In patients with IDDM it raised glucagon (P = 0.0001), but not
C-peptide or insulin, and plasma glucose rose to 8.3 +/- 0.3 (Ala 20 g, P =
0.0006) and 10.0 +/- 1.0 mM (Ala 40 g, P = 0.0094). Catecholamine levels
were unchanged. Terbutaline ingestion raised plasma glucose minimally
(e.g., to 6.3 +/- 0.3 mM, P = 0.0133) in nondiabetic subjects but
substantially, to 10.2 +/- 1.0 (terbutaline 2.5 mg, P = 0.0078) and 14.0
+/- 0.6 mM (terbutaline 5.0 mg, P = 0.0001), in IDDM patients; subcutaneous
terbutaline raised plasma glucose (to a peak of 10.3 +/- 0.7 mM, P =
0.0017) with an initial effect within 10 min, but inhaled terbutaline did
so more slowly. In addition to its direct glycemic actions, terbutaline
stimulated sympathetic neural norepinephrine release (P = 0.0151) and
increased nonesterified fatty acid levels (P = 0.0104), potential indirect
glycemic actions. Glucagon levels were unchanged; insulin levels increased
in the nondiabetic subjects. CONCLUSIONS--These data demonstrate
substantial glycemic responses to Ala and terbutaline, through different
mechanisms, in IDDM patients. Thus, Ala and terbutaline represent potential
new approaches to the treatment, and perhaps the prevention, of iatrogenic
hypoglycemia in IDDM.