Triglyceride glucose index as a surrogate measure of insulin sensitivity in obese adolescents with normoglycemia, prediabetes, and type 2 diabetes mellitus: comparison with the hyperinsulinemic-euglycemic clamp

BackgroundThere is a need for simple surrogate estimates of insulin sensitivity in epidemiological studies of obese youth because the hyperinsulinemic-euglycemic clamp is not feasible on a large scale. Objective(i) To examine the triglyceride glucose (TyG) index (Ln[fasting triglycerides (mg/dL)xfasting glucose (mg/dL)/2]) and its relationship to in vivo insulin sensitivity in obese adolescents (OB) along the spectrum of glucose tolerance and (ii) to compare TyG index with triglyceride/high-density lipoprotein TG/HDL and 1/fasting insulin (1/I-F), other surrogates of insulin sensitivity. Patients and designCross-sectional data in 225 OB with normal glucose tolerance (NGT), prediabetes (preDM), and type 2 diabetes (T2DM) who had a 3-h hyperinsulinemic-euglycemic clamp and fasting lipid measurement. ResultsInsulin-stimulated glucose disposal (Rd) declined significantly across the glycemic groups from OB-NGT to OB-preDM to OB-T2DM with a corresponding increase in TyG index (8.30.5, 8.6 +/- 0.5, 8.9 +/- 0.6, p<0.0001). The correlation of TyG index to Rd was -0.419 (p<0.0001). The optimal TyG index for diagnosis of insulin resistance was 8.52 [receiver operating characteristic-area under the ROC curves (ROC-AUC) 0.750, p<0.0001]. The ROC-AUC for 1/I-F was 0.836(.) In multiple regression analysis, 64.8% of the variance in Rd was explained by TyG index, 1/I-F, body mass index (BMI) z-score, glycemic group, and sex. Conclusion: The TyG index affords an easily and widely available simple laboratory method as a surrogate estimate of insulin sensitivity that could be used repeatedly in large-scale observational and/or interventional cohorts of OB. Although not superior to 1/I-F, TyG index offers the advantage of having a standardized method of measuring triglyceride and glucose, which is not the case for insulin assays.