Screening for insulin resistance in children with abdominal obesity: sex-specific performance of TyG index, FGIR, and VAI

[Purpose] This study aimed to compare the diagnostic performance of the triglyceride-glucose index (TyG), fasting glucose-to-insulin ratio (FGIR), and visceral adiposity index (VAI) for detecting insulin resistance (IR) and to establish sex-specific IR cutoffs in Korean schoolchildren with abdominal obesity.[Methods] This cross-sectional study included 728 fourth- to sixth-grade students (398 boys and 330 girls; mean age, 11.5 ± 1.1 years) from P City, Gyeonggi-do (June 2018-August 2019). Abdominal obesity was defined as waist circumference and waist-to-height ratio ≥ 90th percentile (high-risk subgroup, n = 192). IR was classified using sex-specific homeostasis model assessment of insulin resistance cutoffs (boys ≥ 3.54, girls ≥ 3.69). Receiver operating characteristic analysis with the Youden index was performed to compare TyG index, FGIR, and VAI in the high-risk subgroup.[Results] FGIR demonstrated superior performance in both sexes. The area under the curve (AUC) was 0.939 (95% confidence interval [CI], 0.903-0.976) for boys and 0.894 (95% CI, 0.835-0.954) for girls. Corresponding cutoff values were 8.435 and 7.473, with sensitivities of 94.9% and 91.2% and specificities of 79.6% and 81.2%, respectively. TyG and VAI exhibited lower AUCs (0.726‒0.768 and 0.679‒0.740, respectively). High-risk abdominal obesity was strongly associated with IR (adjusted odds ratio 6.175, 95% CI, 3.958-9.633).[Conclusion] Among Korean school-aged children with abdominal obesity, FGIR outperformed TyG and VAI as surrogate markers of IR. Accounting for pubertal insulin dynamics with sex-specific cutoff values supports the use of FGIR as a practical, low-cost tool for early screening and intervention in high-risk groups.