NEW YORK (Reuters Health) – Low serum levels of sex hormone binding globulin (SHBG) is a better marker for hyperinsulinaemia/insulin resistance in prepubertal obese children than body mass index (BMI), British investigators report.
Dr. P. J. Galloway, of the Royal Hospital for Sick Children in Glasgow, and associates enrolled 25 children, mean age 7.9 years, with BMI>2 standard deviations from the mean for their ages. The researchers measured plasma insulin during an oral glucose tolerance test. In addition, SHBG concentrations were measured in these children and a reference group of 57 healthy, nonobese, prepubertal children.
Among the obese children, 14 exhibited an exaggerated insulin response to oral glucose load suggestive of hyperinsulinism, the British team reports in the December issue of the Archives of Disease in Childhood. However, there were no significant differences in age or BMI between those with and those without an abnormal insulin response.
Circulating SHBG was below normal in 12 of the 14 hyperinsulinaemic patients. All but two of the non-hyperinsulinaemic group exhibited normal SHBG concentrations compared with the reference group. The specificity of SHBG level was 82% and sensitivity 86% in predicting an exaggerated insulin response to glucose.
"Our finding that the circulating SHBG concentration is a better positive predictor of insulin resistance than BMI may facilitate identification of at risk prepubertal children who could be targeted for weight management and lifestyle changes in the hope of reducing their metabolic consequences in later life," Dr. Galloway's team suggests. The results also suggest that SHBG testing may be an appropriate screening test for children attending an obesity clinic.