Context: Fibroblast growth factor 21 (FGF-21), a potent activator of glucose uptake, has been proposed to be related to insulin resistance, metabolic syndrome (MetS), nonalcoholic fatty liver disease (NAFLD), and weight status.
Objective: Our objective was to study the relationships between FGF-21, parameters of MetS, and NAFLD before and after weight loss in obese children.
Design and setting: This was a cross-sectional comparison between obese and normal-weight children and longitudinal 1-yr follow-up study in obese children participating in a lifestyle intervention in a primary care setting.
Patients: Patients included 60 obese and 40 lean children of same age, gender, and pubertal stage.
Intervention: The outpatient 1-yr intervention program was based on exercise, behavior, and nutrition therapy.
Main outcomes measures: We evaluated fasting serum FGF-21, weight status [body mass index (BMI) expressed as sd score (SDS)], body fat, insulin resistance index (homeostasis model assessment), leptin, transaminases, free fatty acids (FFA), waist circumference, blood pressure, and lipids.
Results: Compared with the normal-weight children, obese children demonstrated significantly (P < 0.001) increased FGF-21, leptin, and homeostasis model assessment levels. FGF-21 was significantly (P < 0.05) correlated to BMI, SDS-BMI, FFA, and leptin both in cross-sectional and longitudinal analyses but not to any additional analyzed parameter. Children with and without MetS or NAFLD did not differ significantly with respect to their FGF-21 concentrations. A decrease of SDS-BMI was associated with a significant (P = 0.038) decrease of FGF-21 levels (mean -34%).
Conclusions: FGF-21 concentrations are reversibly increased in obese children and are related to leptin and FFA. However, our data do not support a significant relationship between FGF-21, insulin resistance, and features of MetS or NAFLD in children.
Trial registration: ClinicalTrials.gov NCT00435734.