Context: Obestatin is a peptide hormone derived from the proteolytic cleavage of ghrelin preprohormone. In Prader-Willi syndrome (PWS), the levels of total ghrelin (TG) and acylated ghrelin (AG) are increased, and these hormones are regulated by insulin.

Objective: To analyze the changes in the obestatin levels after glucose loading and to characterize the correlations of obestatin with TG, AG, and insulin.

Design: Plasma obestatin, TG, AG, and insulin levels were measured in PWS children (n = 15) and controls (n = 18) during oral glucose tolerance test (OGTT).

Setting: All subjects were admitted to the Samsung Medical Center.

Interventions: OGTT was performed after an overnight fast.

Main Outcome Measures: The plasma levels of obestatin, TG, AG, and serum insulin were measured at 0, 30, 60, 90, and 120 min after glucose challenge, and AUCs were calculated.

Results: No significant difference in AUC of the plasma obestatin was found between the PWS children and normal obese controls (P = 0.885), although AUCs of AG (P = 0.002) and TG (P = 0.003) were increased in the PWS children. Moreover, There was a negative correlation between AUC of AG and AUC of insulin both in PWS (r= -0.432, P = 0.049) and in control (r= -0.507, P = 0.016). However, AUC of obestatin was not significantly correlated with AUC of insulin (PWS; r=0.168, P = 0.275, control: r=-0.331, P = 0.09).

Conclusions: Our results indicate that plasma obestatin is not elevated in PWS children and is not regulated by insulin both in PWS children and obese controls.