Improving insulin resistance in obese youth: choose your measures wisely.
OBJECTIVE
The purpose of this investigation was to compare the homeostasis model assessment of insulin resistance (HOMA-IR) to more direct measures of insulin action before and after lifestyle interventions in obese Latino youth.


METHODS
Eleven obese Latino boys (age 15.1 ± 1.6 years, body mass index (BMI) percentile 97.3 ± 3.5%) and twenty obese Latina girls (age 14.7 ± 1.8 years, BMI percentile 96.6 ± 3.6%) participated in two distinct lifestyle interventions. Boys participated in a 16-week exercise intervention and girls participated in a 12-week nutrition education program. Insulin sensitivity was determined by the frequently sampled intravenous glucose tolerance test (FSIVGTT) in boys and by a 3-hour oral glucose tolerance test with multiple sampling calculations for the whole-body insulin sensitivity index (WBISI) in girls. HOMA-IR was measured for both groups.


RESULTS
HOMA-IR was correlated at baseline to the FSIVGTT (r = -0.57, p = 0.07) and the WBISI (r = -0.78, p<0.01) and at follow-up (FSIVGTT: r = -0.81, p<0.003; WBISI: r = -0.71, p = 0.001). Post-intervention, insulin sensitivity increased 45% in the boys and 34% in the girls; however, these improvements were not reflected by significant changes in HOMA-IR.


CONCLUSIONS
Improvements in insulin sensitivity following an intervention measured either by the FSIVGTT or an OGTT were not detected by HOMA-IR. Researchers and clinicians should exercise caution in relying on fasting indices, such as HOMA-IR, to determine the impact of lifestyle interventions on insulin sensitivity in overweight youth.
Department of Kinesiology, Arizona State University, Phoenix, AZ, USA. Gabriel.Shaibi@asu.edu
Gabriel Q
GQ
Shaibi
Jaimie N
JN
Davis
Marc J
MJ
Weigensberg
Michael I
MI
Goran
D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D002140:California; D004043:Dietary Fiber / Q000008:administration & dosage; D019422:Dietary Sucrose / Q000008:administration & dosage; D002149:Energy Intake; D005215:Fasting / Q000097:blood*; D005260:Female; D044882:Glucose Metabolism Disorders / Q000097:blood / Q000208:ethnology / Q000503:physiopathology / Q000628:therapy*; D005951:Glucose Tolerance Test; D007722:Health Knowledge, Attitudes, Practice; D006630:Hispanic or Latino; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance / Q000208:ethnology; D016014:Linear Models; D008297:Male; D009765:Obesity / Q000097:blood / Q000208:ethnology / Q000503:physiopathology / Q000628:therapy*; D010353:Patient Education as Topic; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D055070:Resistance Training; D040242:Risk Reduction Behavior; D013997:Time Factors; D016896:Treatment Outcome
D015415:Biomarkers; D001786:Blood Glucose; D004043:Dietary Fiber; D019422:Dietary Sucrose; D007328:Insulin