Basal plasma insulin levels exert a qualitative but not
quantitative effect on glucose-mediated glucose-uptake.
Prato, Stefano Del, Antonio Riccio, Saula Vigili De Kreutzenberg,
Mauro Dorella, Antonio Tiengo, and Ralph A. Defronzo.
Cattedra di Malattie del Metabolismo, University of Padova, Italy
and Division of Diabetes, University of Texas Health Science Center,
and Audie L. Murphy VA Hospital, San Antonio, TX
APStracts 2:0017E, 1995.
We assessed the effect of hyperglycemia on glucose uptake in the
presence of normal basal insulin levels or somatostatin-induced
hypoinsulinemia in 7 normal volunteers during a 200min hyperglycemic
clamp (+9 mmol/L) carried out with 3-3H-glucose and indirect
calorimetry. Hyperglycemia increased glucose uptake to 22.4 2.6 and
21.3 1.6 mol/kg.min with and without insulin replacement,
respectively. Normonsulinemia increased glucose oxidation ( = +4.5
0.6 mol/kg.min) and non-oxidative glucose metabolism ( = +5.2 1.7
mol/kg.min) while with insulinopenia, glucose oxidation did not
change ( = -0.3 0.6 mol/kg.min), and non-oxidative glucose metabolism
increased ( = +8.7 0.8 mol/kg.min). Non-oxidative glucose metabolism
was higher during insulinopenic (13.5 1.8 mol/kg.min) than
normoinsulinemic hyperglycemia (9.8 2.7 mol/kg.min; p<0.01). Plasma
FFA concentration and lipid oxidation were higher with insulinopenia.
Blood lactate and alanine concentrations were greater with
normoinsulinemia. In conclusion: (i) hyperglycemia promotes glucose
uptake by stimulating both non-oxidative and oxidative glucose
disposal; (ii) the ability of hyperglycemia to enhance total body
glucose uptake is similar with and without normoinulinemia; (iii)
although acute insulinopenia does not impair the ability of
hyperglycemia to stimulate glucose uptake, it plays a critical role
in determining the intracellular metabolic fate of glucose taken up
in response to hyperglycemia.
Received 19 September 1994; accepted in final form 26 January
1995.
APS Manuscript Number E384-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.