Glucose production, recycling, and gluconeogenesis in normal and in
diabetic volunteers: a mass isotopomer study with [u-13c]
glucose.
Tayek, John A., and Joseph Katz.
Department of Internal Medicine, Harbor-UCLA Medical Center
APStracts 2:0245E, 1995.
Eight normal controls and nine NIDDM diabetics were, after an
overnight fast, infused for three hours with [6-3H] and [U-13C]c6
glucose at rates from 0.03 to 0.15 mg/kg/min. Plasma glucose and
lactate were assayed by gas chromatography-mass spectroscopy (GC-MS).
Several parameters of glucose metabolism were calculated from the
mass isotopomer distribution. Glucose production (GP) determined with
[6-3H] and [U-13C] glucose agreed closely. GP was 1.9 + 0.16 (1.3 -
2.5 mg/kg/min) in controls and 2.8 + 0.29 (1.7 - 4.5 mg/kg/min) in
diabetes, p<0.05. The correlation in diabetes between plasma
glucose and glucose production (r=0.911, p<0.01) was close.
Recycling of carbon (8% vs 7%), dilution by unlabeled carbon (2 vs
2.3) fold, and dilution via the TCA, 1.5 fold, were similar in
control and diabetics. Gluconeogenesis was 0.90 + 0.08 (0.5 - 1.3
mg/kg/min) in controls and 1.30 + 0.13 (range 0.8 - 1.9) in diabetics
(p<0.05). Gluconeogenesis contribution to GP were 46.6 + 4.0%
(26 - 61%) in the controls and 48.8 + 5.7% (32 - 83%) in diabetics.
We show that using [U-13C]glucose infusion of 2-5% of glucose
turnover (0.03-0.10 mg/kg/min), a large number of parameters of
glucose metabolism may be determined in humans.
Received 18 August 1995; accepted in final form 17 November 1995.
APS Manuscript Number E400-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95