Objective: Former small for gestational age (SGA) children are at risk of both obesity and insulin resistance. Longitudinal studies are required to assess a possible relationship between former SGA status and insulin resistance independent of weight status. We hypothesized that obese children with former appropriate for gestational age (AGA) status improve their insulin resistance during weight loss more effectively compared to obese children with former SGA status.
Methods: A 1-yr longitudinal follow-up study design was adopted in the primary care setting and 341 obese children [8% SGA, mean age 10.5 +/- 0.1 yr, body mass index (BMI) 27.7 +/- 0.2, BMI-standard deviation score (SDS) 2.47 +/- 0.02] were taken for the study. Outpatient 1-yr intervention was based on exercise, behavior and nutrition therapy. We measured insulin resistance index following the Homeostasis model assessment model (HOMA), blood pressure, lipids, glucose, and insulin in all children before and after the 1-yr intervention.
Results: In a multiple linear regression analysis adjusted for age, gender, and pubertal stage, changes of HOMA were significantly related to changes of BMI-SDS (-2.55 per loss of 1 BMI-SDS unit; p < 0.001) and SGA status (+2.05 for SGA children; p < 0.001). Changes of BMI-SDS together with gender and age explained 10% of the variance of changes of HOMA, while SGA status explained an additional 4%. After adjustment for age, sex, pubertal stage, and BMI-SDS, former SGA status was not significantly related to any other considered cardiovascular risk factor.
Conclusions: Change of weight status predicted change of HOMA in obese children participating in a lifestyle intervention. Changes of HOMA were also predicted by former SGA status supporting that former SGA status influences insulin resistance.
Trial registration: ClinicalTrials.gov NCT00435734.