gms | German Medical Science

Objectives: Insulin resistance (IR) is frequently observed in childhood obesity. It represents a link between obesity and type 2 diabetes or cardiovascular disease and can track into adult life. Several markers, e.g. fasting insulin, glucose/insulin ratio, HOMA, HbA1c and CRP, have been suggested as surrogate markers for screening purposes in adults (Singh, 2010), as the gold standard method to measure insulin sensitivity (the hyperinsulinemic euglycemic clamp) is very labor- and time-intensive and thus not feasible in epidemiological research. In children, however, screening data on insulin resistance is rare, especially from large-scale epidemiological studies. Moreover, there is lack of adequate reference values for the respective markers of insulin resistance in children. The aim of this study is to describe levels of surrogate markers for insulin resistance in a population-based cross-sectional study of European children, aged 2-9 years. The influence of age on the distributions is evaluated, as well as the effect of BMI, waist circumference and sex.

Material and methods: During the baseline survey of the IDEFICS study in 2007/2008 fasting venous blood was collected from 9,185 2 to 9 year old children from eight European countries. 7,246 children could be included into the statistical analyses, because all parameters of interest were available for them. Potentially confounding factors were taken into account.

Results: Insulin and glucose levels and the derived HOMA index of children in the IDEFICS baseline survey increased with age and weight group (BMI classes according to Cole) of the children. CRP as a marker of inflammation also increased with the weight group of the children but remained stable with growing age. Data analysis showed lower and age-dependent biomarker concentrations for children in the IDEFICS cohort compared to normal ranges for adults. Concentrations of most markers differed slightly between the sexes. Insulin, glucose, HOMA index and CRP, but not HbA1c were significantly correlated with BMI and waist circumference in an age-adjusted Spearman correlation analysis.

Conclusion: This study shows that most surrogate markers for IR are elevated in overweight/ obese children already before puberty. The increase of insulin and glucose concentrations with age underlines that age-dependent reference values are needed for children.