Link between omentin-1, obesity and insulin resistance in children: Findings from a longitudinal intervention study.

OBJECTIVE: The adipokine omentin-1 has been suggested to be inversely associated with obesity and insulin resistance in humans. We studied the relationships between omentin-1, parameters of fat mass, insulin resistance, lipids and blood pressure in children with obesity in a longitudinal study. METHODS: We analysed omentin-1 concentrations in 23 normal-weight children and in 82 children with obesity participating in a one-year lifestyle intervention. In the children with obesity, omentin-1, bioactive and conventional leptin, thyroid hormones (thyroid-stimulating hormone, free thyroxine 4, free triiodothyronine), body mass index, waist circumference, body fat based on skin-fold measurements and bioimpedance analyses, lipids, insulin resistance as homeostatic model assessment of insulin resistance (HOMA-IR) and blood pressure were determined at baseline and 1 year later. Furthermore, we measured omentin-1 concentrations 1 year after the end of the lifestyle intervention. RESULTS: The omentin-1 concentrations were significantly (P = .008) lower in children with obesity compared to normal-weight children (296 ± 108 ng ml-1 vs. 232 ± 99 ng ml-1 ). Omentin-1 concentrations increased significantly (P < .001) in children with obesity and substantial weight loss (35 ± 55 ng ml-1 ), while omentin-1 concentrations did not change significantly (P = .750) in children with obesity without weight loss (-5 ± 108 ng ml-1 ) during the intervention. Substantial weight loss after the end of intervention led to a significant (P < .001) increase of omentin-1 concentrations (+64 ± 14 ng ml-1 ). Omentin-1 was significantly and negatively associated with HOMA-IR both in cross-sectional (r = -.27, P = .006) and longitudinal analyses (r = -.33, P = .001). Omentin-1 concentrations were not related to pubertal stage, sex or thyroid hormones. CONCLUSIONS: Our data do support the hypothesis that omentin-1 is reversibly decreased in obesity and is a link between obesity and insulin resistance.