A longitudinal study of serum insulin and insulin resistance as predictors of weight and body fat gain in African American and Caucasian children

Abstract

<div class="section"> <a class="named-anchor" id="S1"> <!-- named anchor --> </a> <h5 class="section-title" id="d10810414e251">Background</h5> <p id="P1">The influence of insulin and insulin resistance (IR) on children’s weight and fat gain is unclear. </p> </div><div class="section"> <a class="named-anchor" id="S2"> <!-- named anchor --> </a> <h5 class="section-title" id="d10810414e256">Objective</h5> <p id="P2">To evaluate insulin and IR as predictors of weight and body fat gain in children at high-risk for adult obesity. We hypothesized that baseline IR would be positively associated with follow-up BMI and fat mass. </p> </div><div class="section"> <a class="named-anchor" id="S3"> <!-- named anchor --> </a> <h5 class="section-title" id="d10810414e261">Subjects/Methods</h5> <p id="P3">249 healthy African American and Caucasian children, age 6–12y, at high-risk for adult obesity because of early-onset childhood overweight and/or parental overweight, were followed for up to 15y with repeated BMI and fat mass measurements. We examined baseline serum insulin and HOMA-IR as predictors of follow-up BMI Z score and fat mass by DEXA in mixed model longitudinal analyses accounting for baseline body composition, pubertal stage, sociodemographic factors, and follow-up interval. </p> </div><div class="section"> <a class="named-anchor" id="S4"> <!-- named anchor --> </a> <h5 class="section-title" id="d10810414e266">Results</h5> <p id="P4">At baseline, 39% were obese (BMI ≥95th percentile for age/sex). Data from 1,335 annual visits were examined. Children were followed for an average of 7.2±4.3y, with a maximum follow up of 15 years. After accounting for covariates, neither baseline insulin nor HOMA-IR was significantly associated with follow up BMI (p’s&gt;.26), BMIz score (p’s&gt;.22), fat mass (p’s&gt;.78), or fat mass percentage (p’s&gt;.71). In all models, baseline BMI (p&lt;.0001), body fat mass (p&lt;.0001), and percentage fat (p&lt;.001) were strong positive predictors for change in BMI and fat mass. In models restricted to children without obesity at baseline, some but not all models had significant interaction terms between body adiposity and insulinemia/HOMA-IR that suggested less gain in mass among those with greater insulin or insulin resistance. The opposite was found in some models restricted to children with obesity at baseline. </p> </div><div class="section"> <a class="named-anchor" id="S5"> <!-- named anchor --> </a> <h5 class="section-title" id="d10810414e271">Conclusions</h5> <p id="P5">In middle childhood, BMI and fat mass, but not insulin or IR, are strong predictors of children’s gains in BMI and fat mass during adolescence. </p> </div>