The distinction of metabolically ‘healthy’ from metabolically ‘unhealthy’ obese children and adolescents

Abstract

Background: A majority of obese children show metabolic disturbances such as impaired glucose tolerance, insulin resistance, dyslipidemia and hypertension. However, these complications are not present in every obese child. In general, healthy obesity describes the absence of any metabolic disorder including type 2 diabetes, dyslipidemia and hypertension in an obese individual (Bluher, 2010). Objective and hypothesis: The aim of our study was to identify and compare metabolically ‘healthy’ with metabolically ‘unhealthy’ obese children. It is hypothesized that an unfavourable metabolic profile, rather than a high BMI, is associated with a higher risk for type 2 diabetes and cardiovascular disease. Methods: We retrospectively analysed data from 162 obese (mean ± SD BMI SDS: 2.7 ± 0.6) children and adolescents (91 females) aged 10 to 18 years (age: 13.4 ± 1.8 yrs) who underwent an OGTT between May 2004 and January 2012. Plasma glucose, insulin, HDL-cholesterol and triglyceride concentrations were measured. Metabolically ‘healthy’ obese (MHO) children were defined as having none of the components of the MetS except obesity, whereas metabolically unhealthy obese (MUO) were defined as having at least one additional component of the MetS (Zimmet et al., 2007). Results: 29 (18 %) of the subjects did not have any component of the MetS. There were no differences in age (MHO: 12.9 ± 1.6 yrs; MUO: 13.4 ± 1.8 yrs) nor BMI-SDS (2.6 ± 0.6 vs 2.8 ± 0.6) between both groups. Fasting glucose was comparable (88 ± 6 mg/dl vs 90 ± 8 mg/dl). Fasting insulin (16 ± 9 µU/ml vs 24 ± 13 µU/ml; p<0.001), 2-hour glucose (107 ± 15 vs 118 ± 24; p=0.002), 2-hour insulin (75 ± 63 µU/ml vs 128 ± 114 µU/ml; p=0.005), HOMA-IR (3.5 ± 2.3 vs 5.5 ± 3.1; p<0.001) and HOMA-%B (255±174 vs 346±240; p=0.006) were lower in the MHO group. None of the subjects in the MHO had impaired fasting glucose or impaired glucose tolerance, whereas as 36 (27%) of the MUO had prediabetes. Conclusion: About 20% of the studied obese children and adolescents are metabolically ‘healthy’. Metabolically ‘healthy’ obese individuals presented a significantly better glucose tolerance, insulin sensitivity, and beta-cell function compared to metabolically ‘unhealthy’ obese children. Early identification of metabolically ‘healthy’ versus ‘unhealthy’ obese children is recommended in order to provide better targeted and personalized therapies.