Diabetes, Vol 38, Issue 10 1238-1244, Copyright © 1989 by American Diabetes Association
Contribution of insulin resistance to catabolic effect of prednisone on leucine metabolism in humans
T Zimmerman, F Horber, N Rodriguez, WF Schwenk and MW Haymond
Department of Pediatrics, Mayo Clinic and Foundation, Rochester, Minnesota 55905.
To determine the role insulin resistance may play in the catabolic effect
of high-dose prednisone therapy, healthy volunteers were studied on four
occasions with the hormone-clamp technique at two insulin infusion rates.
Subjects were studied after 5 days of prednisone (60 mg/day) or no steroid
treatment and were infused with somatostatin, glucagon, growth hormone,
[3H]glucose, [14C]leucine, and insulin (0.1 or 0.2 mU.kg-1.min-1). At each
rate of insulin infusion, the rate of leucine oxidation was increased (P
less than .001) after steroid treatment. Leucine flux, an indicator of
whole-body proteolysis, was similar in the presence or absence of steroid
treatment (2.26 +/- 0.08 vs. 2.13 +/- 0.04 mumol.kg-1.min-1, respectively)
at the lower rate of insulin infusion but was higher during steroid
treatment (2.18 +/- 0.06 vs. 1.84 +/- 0.13 mumol.kg-1.min-1) at the
0.2-mU.kg-1.min-1 insulin infusion. Steroid pretreatment had no significant
effect on the nonoxidative rates of leucine disappearance. These data
provide strong evidence that the protein wasting associated with
glucocorticosteroid therapy is in part the result of steroid-induced
resistance to the antiproteolytic effect of insulin and an increase in the
oxidation (and thus wasting) of one essential amino acid, leucine.