Regulation of ghrelin is related to estimated insulin sensitivity in obese children

Objective: To investigate whether ghrelin concentrations and their changes during weight loss in obese children are associated with parameters of glucose and insulin metabolism. Design: Total plasma ghrelin, insulin and glucose were measured during oral glucose tolerance testing before and after diet-induced weight loss over 6 weeks. Setting: In-patient rehabilitation program in a pediatric hospital. Participants: Twenty-three obese children (age 10-16 years) and 11 normal weight controls (age 10-15 years). Outcome measures: Changes in ghrelin concentrations during weight loss and correlation analysis of changes in ghrelin and changes in parameters of glucose and insulin metabolism. After data collection, subgroup analysis of obese patients with high, medium and low estimated insulin sensitivity whole-body insulin sensitivity index (WBISI) was performed. Results: Weight loss increased the area under the curve (AUC) of ghrelin by 26% (P<0.001). The increase in ghrelin AUC correlated significantly with improved estimated insulin sensitivity (WBISI) (r=0.69, P<0.001). The independent predicting effect of WBISI was confirmed in multivariate analysis. In children with low WBISI, ghrelin reached the level of control values after weight loss. In children with high WBISI, ghrelin increased markedly above control levels. Conclusions: Changes in ghrelin are independently associated with changes in glucose and insulin metabolism. The increase in plasma ghrelin above control levels was limited to obese children with high WBISI.