Triglyceride-glucose index identifies early metabolic stress and β-cell vulnerability in pediatric obesity

The triglyceride-glucose (TyG) index is a simple marker of insulin resistance and metabolic risk, but whether it captures early β-cell vulnerability in children with obesity remains unclear. This study aimed to determine whether TyG index is associated with indices of β-cell function and metabolic risk beyond the severity of obesity in children.

This cross-sectional study included children/adolescents with obesity who underwent comprehensive metabolic evaluation, including oral glucose tolerance testing (OGTT). Participants were stratified by TyG tertiles and conventional metabolic classifications. Insulin sensitivity, insulin secretion, and β-cell disposition indices were derived from OGTT data. Associations between TyG, body mass index (BMI) Z-score, and metabolic biomarkers were assessed using correlation, multivariate regression, and unsupervised clustering analyses.

Despite comparable severity of obesity, children in the highest TyG tertile exhibited a markedly adverse metabolic profile, characterized by higher glycemic and hepatic markers and reduced insulin sensitivity. OGTT-derived indices showed lower insulin sensitivity and reduced secretion-sensitivity coupling with increasing TyG, while hybrid disposition index remained preserved across TyG tertiles. TyG showed broader and more robust associations with metabolic and β-cell-related indices than BMI Z-score and was independently associated with β-cell disposition indices in multivariate models. Cluster analysis further revealed distinct metabolic phenotypes among children with similar degrees of obesity, with TyG distinguishing high-risk profiles characterized by impaired insulin sensitivity and potential β-cell vulnerability. Comparisons across metabolic states further indicated that TyG provided metabolic information not fully captured by conventional categorical definitions of metabolic dysfunction.

The TyG index is associated with a dimension of metabolic stress and potential β-cell vulnerability in pediatric obesity that is not adequately reflected by the severity of obesity alone. By identifying metabolic heterogeneity not fully captured by BMI-based assessment, TyG may complement conventional risk assessment and support metabolic risk stratification in children with obesity.