Changes of ghrelin following oral glucose tolerance test in obese children with insulin resistance

Abstract

To characterize changes in ghrelin levels in response to oral glucose tolerance test (OGTT) and to correlate changes in ghrelin levels with changes in insulin and glucose following OGTT in Chinese obese children of Tanner I and II stage with insulin resistance. 22 obese children with insulin resistance state were divided into four groups according to their Tanner stage and gender: boys of Tanner I (BT-I), boys of Tanner II (BT-II), girls of Tanner I (GT-I), girls of Tanner II (GT-II). Ghrelin, insulin and glucose were measured at 0, 30, 60 and 120 min following OGTT. The control children with normal BMI were divided into control boys of Tanner I (CBT-I, n = 6), control boys of Tanner II (CBT-II, n = 5), control girls of Tanner I (CGT-I, n = 6), control girls of Tanner II (CGT-II, n = 5). Fasting serum ghrelin levels were analyzed. Ghrelin levels were lower in obese groups. Ghrelin levels of control group decreased in Tanner II stage (CGT-I vs CGT-II t = -4.703, P = 0.001; CBT-I vs CBT-II t = -4.794, P = 0.001). Basal ghrelin levels in BT-II decreased more significantly than that in BT-I group (t = 2.547, P = 0.029). Ghrelin levels expressed a downward trend after OGTT among obese children. The decrease in ghrelin levels at 60 min with respect to basal values was 56.9% in BT-I. Ghrelin concentrations at 0 min correlated directly with glucose level at 0 min in BT-I (r = 0.898, P = 0.015). There wasn't a significant correlation of ghrelin changes with glucose changes and insulin changes during OGTT in obese children with insulin resistance. In conclusion, in obese children with insulin resistance, ghrelin levels decreased with advancing pubertal stage. Ghrelin secretion suppression following OGTT was influenced by gender and pubertal stage. Baseline ghrelin levels and ghrelin suppression after OGTT did not significantly correlate with the degree of insulin resistance and insulin sensitivity.