Relationship between Serum Ghrelin and Insulin Resistance in Obese Children and Adolescents

Kim, Soo Young; Shin, Jung Yeon; Jung, Min Jee; Choi, Byung Min; Lee, Jung Hwa; Lee, Kee Hyoung

Abstract

PURPOSE
Ghrelin, a 28-amino-acid peptide predominantly produced by the stomach, is endogenous ligand of growth hormone secretagogue receptor and potent stimulator of growth hormone. Ghrelin is also proposed to be orexigenic peptide that induce weight gain by increasing food intake. In general, ghrelin level increase preprandially and decrease after meals and ghrelin is reduced in obese, insulin resistance adults. There is a few available data of ghrelin level in obese children. The aim of this study was to determine whether there was difference of serum ghrelin level between obese and lean children and to evaluate the relationship between ghrelin and insulin resistance.
METHODS
The study population consisted of 104 Children (65 males and 39 females) aged 8.0 to 15.0 years. We measured serum glucose and lipid profiles after 8 hr of fasting. Serum insulin and ghrelin were measured by radioimmunoassay. We compared serum ghrelin level between 52 obese children whose body mass index (BMI) greater than the 95th percentile for age and sex and 31 lean children and evaluated the relationship of ghrelin with BMI, fasting glucose, lipid profile and insulin resistance. We also compared serum ghrelin level of fasting and two-hour postprandial state by oral glucose tolerance test in 23 obese children.
RESULTS
Mean serum ghrelin concentrations were 445.4 pg/mL in obese children, 504.9 pg/mL in lean children, but not different significantly. The decrease in serum ghrelin with advancing pubertal stage was significantly marked between prepuberty and overt puberty group (P<0.05). The fasting serum ghrelin concentration were negatively associated with height (r=-0.25, P<0.05), weight (r=-0.28, P<0.01), BMI (r=-0.21, P<0.05), fasting insulin concentration (r=-0.27, P<0.01) and HOMA-IR (r=-0.24, P<0.05). After two-hour postprandial state in obese children group, serum ghrelin level were decreased than fasting state (P<0.01).
CONCLUSION
Serum ghrelin had no significant difference between obese and lean children but negatively correlated with body mass index and ghrelin were associated with fasting insulin concentration and HOMA-IR. This findings suggest that ghrelin is regulated by feeding state and also modulated by insulin secretion.