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Association between insulin sensitivity and post-glucose challenge plasma insulin values in overweight Latino youth
Marc J Weigensberg1, Martha L Cruz, Michael I Goran
1Department of Physiology and Biophysics, University of Southern California, Los Angeles, California 90089, USA.
Insights
For overweight children at risk of type 2 diabetes, 2-hour insulin levels and post-glucose challenge insulin sensitivity (SI) indices are better indicators of SI than fasting values, especially when considering body composition.
Area of Science:
- Pediatric Endocrinology
- Metabolic Health
- Type 2 Diabetes Risk Assessment
Background:
- Overweight peripubertal Latino children face increased risk for type 2 diabetes.
- Accurate assessment of insulin sensitivity (SI) is crucial for early detection and intervention.
- Existing methods for estimating SI may be influenced by body composition.
Purpose of the Study:
- To evaluate the association between directly measured insulin sensitivity (SI) and various oral glucose tolerance test (OGTT)-derived insulin values and SI indices.
- To determine which OGTT-derived measures best correlate with gold-standard SI measurements in at-risk children, independent of body composition.
Main Methods:
- Thirty overweight Latino children (aged 8-13) with a family history of type 2 diabetes underwent an OGTT and a frequently sampled intravenous glucose tolerance test (FSIGTT).
- Fasting and 2-hour plasma insulin, OGTT-derived SI indices, and FSIGTT-derived SI were compared.
- Analyses were performed before and after adjusting for body composition (total body fat, lean tissue mass, or BMI).
Main Results:
- Directly measured SI showed significant correlations with fasting insulin, 2-hour insulin, and all OGTT-derived SI indices.
- After adjusting for body composition, associations between SI and fasting insulin or fasting SI indices were no longer significant.
- However, 2-hour insulin values and post-glucose challenge SI indices maintained significant independent associations with SI.
Conclusions:
- In overweight peripubertal Latino children at risk for type 2 diabetes, 2-hour plasma insulin and post-challenge SI indices are superior correlates of directly measured SI compared to fasting values, even after accounting for body composition.
- The 2-hour insulin level may be a more reliable single-sample indicator for clinical and epidemiological estimation of SI in this population, particularly when combined with body composition assessment.
Objective:
To determine associations between directly measured insulin sensitivity (SI) and oral glucose tolerance test (OGTT)-derived plasma insulin values, or calculated SI indices, in overweight peripubertal Latino children at risk for type 2 diabetes.
Research Design And Methods:
Thirty overweight Latino children with a family history of type 2 diabetes, aged 8-13 years, Tanner stages 1-2, underwent an OGTT. Fasting and 2-h plasma insulin values and OGTT-derived SI indices were compared with SI derived from a frequently sampled intravenous glucose tolerance test (FSIGTT) with minimal model analysis, before and after adjustment for total body fat and lean tissue mass, or BMI.
Results:
FSIGTT-derived SI for all subjects was 1.62 +/- 0.78 x 10(-4) min (-1) x (microU/ml), with no sex differences. SI correlated (all P values < 0.001) with fasting (r = -0.57) and 2-h (r = -0.58) plasma insulin and all SI indices (r = -0.57 to 0.67). After adjusting for total body fat and lean tissue mass, or BMI, the associations between SI and either fasting insulin or fasting SI indices were no longer significant. However, the 2-h insulin and post-glucose challenge SI indices maintained significant independent associations with SI, even after adjustment for body composition.
Conclusions:
In overweight, peripubertal Latino children at risk for type 2 diabetes, the 2-h plasma insulin value and postchallenge SI indices are better independent correlates of SI than fasting values, after accounting for body composition. The 2-h insulin may therefore be superior to fasting insulin as a single blood sample value for clinical or epidemiological estimates of SI, especially when combined with assessment of body composition.