Ethnic differences in insulin action in obese African-American and Latino adolescents.
BACKGROUND
African-American children have a greater acute insulin response to iv glucose (AIR) compared with Latino children despite a similar degree of insulin resistance and body composition. It is unclear whether African-Americans demonstrate an exaggerated insulin response to an oral glucose challenge and whether any differences are seen in more obese children in advanced pubertal development.


OBJECTIVE
Our objective was to compare glucose and insulin indices derived from an oral glucose tolerance test (OGTT) and iv glucose tolerance test (IVGTT) in sedentary, obese African-American (n=59) and Latino (n=83) adolescents.


METHODS
Glucose and insulin incremental area under the curve was measured during an OGTT, and AIR, insulin sensitivity, disposition index, and glucose effectiveness were assessed during an IVGTT. Body composition was assessed via dual-energy x-ray absorptiometry and magnetic resonance imaging.


RESULTS
From the OGTT, glucose and insulin IAUC were 29.1 and 22.5% lower (P=0.01) in African-Americans compared with Latino adolescents. From the IVGTT, insulin sensitivity and glucose effectiveness were 41.7% (P<0.01) and 50.0% (P=0.02) lower in African-Americans compared to Latinos. AIR (P=0.001) and disposition index (P=0.02) were 63.0 and 48.8% higher in African-Americans, respectively, compared with Latinos. These findings persisted after controlling for body composition and fat distribution.


CONCLUSIONS
There were marked differences in glucose and insulin indices derived from the OGTT and IVGTT. African-Americans were more insulin resistant as measured by the IVGTT compared with the Latino adolescents. However, the well-described hyperinsulinemia in response to iv glucose was not observed after oral glucose in African-American adolescents.
Hasson
Rebecca E
RE
University of Southern California, Department of Preventive Medicine, 2250 Alcazar Street, Clinical Sciences Center, Los Angeles, California 90033, USA.
Adam
Tanja C
TC
Davis
Jaimie N
JN
Weigensberg
Marc J
MJ
Ventura
Emily E
EE
Lane
Christianne J
CJ
Roberts
Christian K
CK
Goran
Michael I
MI
D015502:Absorptiometry, Photon; D000293:Adolescent; D001741:Black or African American; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D001823:Body Composition; D005260:Female; D005951:Glucose Tolerance Test; D006630:Hispanic or Latino; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000208:ethnology*; D008297:Male; D009765:Obesity / Q000208:ethnology* / Q000378:metabolism*; D012044:Regression Analysis
D001786:Blood Glucose; D007328:Insulin
Diabetes Care. 2008 Jul;31(7):1445-7
18417751
Obesity (Silver Spring). 2009 Aug;17(8):1542-8
19247280
Diabetes Care. 1996 Sep;19(9):1018-30
8875104
J Clin Endocrinol Metab. 1990 Jun;70(6):1644-50
2189887
Diabetes Care. 2002 Dec;25(12):2184-90
12453958