Relations of fatness and fitness to fasting insulin in black and white adolescents.
OBJECTIVE
To determine in black and white youths the degree to which fatness and cardiovascular fitness (CVF) explained independent proportions of the variance in fasting insulin concentrations.


METHODS
Youths 14 to 18 years of age (n = 278) were studied. Insulin was measured after a 12-hour fast. Percent body fat (%BF) was measured with dual-energy x-ray absorptiometry. CVF was determined with a multistage treadmill test.


RESULTS
Girls had higher %BF and lower CVF than boys. Whites were higher in CVF than blacks. There was a race by sex interaction for fasting insulin concentration, such that black girls had the highest and white girls had the lowest concentrations. When %BF and CVF was controlled statistically, this interaction was no longer significant. Multiple regression models that controlled for race, sex, and their interaction showed that (1) both higher %BF and lower CVF were significantly associated with higher insulin concentrations; (2) there were significant interactions with sex, such that the deleterious effects of low CVF and high %BF were greater in boys than in girls; (3) there was a significant CVF-%BF interaction, such that youths who were both fit and lean had especially low insulin concentrations; and (4) sex-specific regressions showed that both %BF and CVF explained significant independent proportion of the insulin variance for the boys but that only %BF did so for the girls.


CONCLUSIONS
Interventions to prevent hyperinsulinemia in youths should be designed both to minimize fatness and maximize CVF.
Gutin
Bernard
B
Georgia Prevention Institute, Department of Pediatrics, Medical College of Georgia, Augusta, USA. bgutin@mail.mcg.edu
Yin
Zenong
Z
Humphries
Matthew C
MC
Hoffman
William H
WH
Gower
Barbara
B
Barbeau
Paule
P
D000293:Adolescent; D044383:Black People; D001786:Blood Glucose; D015992:Body Mass Index; D002319:Cardiovascular System; D005215:Fasting / Q000097:blood*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D009765:Obesity / Q000097:blood*; D010809:Physical Fitness / Q000502:physiology; D012044:Regression Analysis; D044465:White People
D001786:Blood Glucose; D007328:Insulin