Age-related insulin resistance changes in children and adolescents and its impact on the accuracy of diagnosis of metabolic syndrome

Purpose: Although insulin resistance (IR) varies with age and puberty in children and adolescents, most previous attempts to determine cutoff values for IR indices overlook factor. This study assesses age-related differences in IR index values and evaluates how diagnostic performance varies by age when using a uniform cutoff for diagnosing metabolic syndrome (MetS) without considering age. Methods: We analyzed age-related differences in IR indices (the homeostatic model assessment of insulin resistance [HOMA-IR], triglyceride-glucose [TyG] index, and triglyceride/high-density lipoprotein cholesterol [TG/HDL-C] ratio) among 1,641 participants in the 2019–2021 Korea National Health and Nutrition Examination Survey. We also examined IR index values for diagnosing MetS in 1,574 participants. Results: IR indices showed significant age-related variations in group-comparison tests, with a peak at ages 12–13 years in males and 11–13 years in females (P<0.001 for the HOMA-IR, P<0.005 for the TG/HDL-C ratio in both males and females, and P=0.003 for the TyG index in females). Applying a uniform cutoff derived from receiver operating characteristic curve analysis for diagnosing MetS showed substantial age-related variation in diagnostic accuracy, with standard deviationto-mean ratios of age-specific accuracy of >10% for the HOMA-IR and >5% for the TyG index, while showing minor variation (<5%) for the TG/HDL-C ratio. Using age-specific percentiles for the HOMA-IR (80th of the general population) and TyG index (80th of those without MetS) reduced these variations to <5% while maintaining similar diagnostic performance. Conclusion: This study highlights the importance of age-related variation in IR in children and adolescents.