AJP - Endocrinology and Metabolism, Vol 259, Issue 5 E626-E632, Copyright © 1990 by American Physiological Society

ARTICLES

Dexamethasone increases glucose cycling, but not glucose production, in healthy subjects

A. Wajngot, A. Khan, A. Giacca, M. Vranic and S. Efendic
Department of Endocrinology, Karolinska Hospital, Stockholm, Sweden.

We established that measurement of glucose fluxes through glucose-6-phosphatase (G-6-Pase; hepatic total glucose output, HTGO), glucose cycling (GC), and glucose production (HGP), reveals early diabetogenic changes in liver metabolism. To elucidate the mechanism of the diabetogenic effect of glucocorticoids, we treated eight healthy subjects with oral dexamethasone (DEX; 15 mg over 48 h) and measured HTGO with [2-3H]glucose and HGP with [6-3H]glucose postabsorptively and during a 2-h glucose infusion (11.1 mumol.kg-1.min-1). [2-3H]- minus [6-3H]glucose equals GC. DEX significantly increased plasma glucose, insulin, C peptide, and HTGO, while HGP was unchanged. In controls and DEX, glucose infusion suppressed HTGO (82 vs. 78%) and HGP (87 vs. 91%). DEX increased GC postabsorptively (three-fold) P less than 0.005 and during glucose infusion (P less than 0.05) but decreased metabolic clearance and glucose uptake (Rd), which eventually normalized, however. Because DEX increased HTGO (G-6-Pase) and not HGP (glycogenolysis + gluconeogenesis), we assume that DEX increases HTGO and GC in humans by activating G-6-Pase directly, rather than by expanding the glucose 6-phosphate pool. Hyperglycemia caused by peripheral effects of DEX can also contribute to an increase in GC by activating glucokinase. Therefore, measurement of glucose fluxes through G-6-Pase and GC revealed significant early effects of DEX on hepatic glucose metabolism, which are not yet reflected in HGP.

This article has been cited by other articles:

				S. C. Rathman, B. Lewis, and R. J. McMahon Acute glucocorticoid treatment increases urinary biotin excretion and serum biotin Am J Physiol Endocrinol Metab, March 1, 2002; 282(3): E643 - E649. [Abstract] [Full Text] [PDF]

				P. N. Båvenholm, J. Pigon, C.-G. Östenson, and S. Efendic Insulin Sensitivity of Suppression of Endogenous Glucose Production Is the Single Most Important Determinant of Glucose Tolerance Diabetes, June 1, 2001; 50(6): 1449 - 1454. [Abstract] [Full Text]

				V. Rigalleau, C. Binnert, K. Minehira, N. Stefanoni, P. Schneiter, E. Henchoz, O. Matzinger, C. Cayeux, E. Jéquier, and L. Tappy In Normal Men, Free Fatty Acids Reduce Peripheral but Not Splanchnic Glucose Uptake Diabetes, April 1, 2001; 50(4): 727 - 732. [Abstract] [Full Text]

				M. Dirlewanger, P. Schneiter, E. Jequier, and L. Tappy Effects of fructose on hepatic glucose metabolism in humans Am J Physiol Endocrinol Metab, October 1, 2000; 279(4): E907 - E911. [Abstract] [Full Text] [PDF]