Effect of oral glucose administration on ghrelin levels in obese children

Objective: Coexpression of GH secretagogue receptor and ghrelin in the pancreas suggests that this peptide is involved in glucose metabolism. Previous reports in adult humans have demonstrated that plasma ghrelin levels decrease after oral glucose administration. However, no data are available in children. Therefore, the aim of this study was to analyze the response of plasma ghrelin levels in obese children after oral glucose administration. Subjects and methods: Twenty-eight obese children ranging from Tanner I to Tanner V were studied. All subjects were given 0.75 g/kg (maximum 75 g) glucose solution after overnight fasting. Ghrelin, insulin, glucose and IGF-binding-protein-1 were determined at 0, 30, 60 and 120 min of the oral glucose tolerance test (OGTT). Results: Basal plasma ghrelin levels were significantly lower than in the respective control groups. These levels decreased significantly during OGTT in obese children, reaching a nadir of 28 +/- 9% at 60 min in parallel with the maximum increase in glucose levels and previous to maximum insulin levels. Conclusion: The rapid fall in plasma ghrelin concentration in obese children after glucose load suggests a mechanism for the control of appetite after food intake.