Vol. 277, Issue 5, E905-E914, November 1999
Ethnicity affects the postprandial regulation of
glycogenolysis
Ashok
Balasubramanyam1,
Siripoom
McKay1,2,
Prashant
Nadkarni1,
Arun S.
Rajan1,
Armandina
Garza3,
Valory
Pavlik3,
J. Alan
Herd4,
Farook
Jahoor2, and
Peter J.
Reeds2
1 Division of Endocrinology and
4 Section on Atherosclerosis,
Department of Medicine,
2 Department of Pediatrics,
Children's Nutrition Research Center, and
3 Department of Community
Medicine, Baylor College of Medicine, Houston, Texas
We investigated the
effect of nutrient intake on glucose metabolism in normal
Mexican-Americans (n = 6) and
European-Americans (n = 6). Subjects
were studied after an 18-h fast and after 5-6 h of ingestion of
hourly meals that supplied 6.35 or 12.75 µmol glucose · kg
1 · min1.
Endogenous glucose production (EGP), gluconeogenesis (GNG), and
glycogenolysis (GLY) were estimated by mass isotopomer analysis with
[U-13C]glucose
infusions. Fasting EGP, GNG, and GLY did not differ between the groups.
Food ingestion lowered the molar rate of GNG by only 31%. However,
while consuming the lower quantity of nutrients, Mexican-Americans had
higher plasma glucose (P < 0.05), a
39% higher rate of EGP (P < 0.05), and a 68% (P < 0.025) higher rate of GLY than the European-Americans. At the higher
intake, EGP and GLY were suppressed completely in both groups. There
was a linear relationship between insulin concentrations, EGP, and GLY in both groups, but the slope of the line was significantly
(P < 0.05) greater in the
European-Americans. We conclude that the sensitivity of GLY to nutrient
intake differs between ethnic groups and that this may play a role in
the increased predisposition of Mexican-Americans to type II diabetes.
Mexican-American; type II diabetes; gluconeogenesis
