Interactive and Joint Effects of Obesity and Insulin Resistance on Hypertension in Adolescents and the Mediating Role of Insulin Resistance—Five Provinces, China

<b>Background:</b> The global prevalence of pediatric hypertension is on the rise. Adolescence is a period of high prevalence of childhood hypertension. Obesity and insulin resistance (IR) are important risk factors in the development of hypertension, but their interaction and combined effects on adolescent hypertension remain unclear. <b>Methods:</b> This cross-sectional study utilized data from the China National Nutrition and Health Surveillance of Children and Lactating Mothers (2016-2017). A total of 7031 adolescents aged 12-17 years from five provinces were included. The triglyceride-glucose index (TyG) was used as an indicator of IR. Multivariable logistic regression and generalized linear mixed-effect models were used to assess the interaction and joint effects of IR and obesity (measured by body mass index [BMI] and waist circumference [WC]) on hypertension. Relative excess risk due to interaction (RERI), proportion attributable to interaction (AP), and synergy index (SI) were calculated to evaluate additive interactive effects. Mediation analysis explored the potential mediating role of the TyG in the association between obesity and hypertension. <b>Results:</b> IR and obesity were positively associated with adolescent hypertension (<i>p</i> < 0.001). Interaction analyses revealed a robust synergistic interaction between obesity and IR on hypertension, with the AP being approximately 40% (<i>p</i> < 0.001). TyG significantly mediated the association between obesity and adolescent hypertension (6.30% for high BMI and 8.54% for high WC, both <i>p</i> < 0.001). <b>Conclusions:</b> This study suggests that obesity and IR could synergistically contribute to the prevalence of hypertension in adolescents. For the primary prevention and management of hypertension in adolescents, strategies targeting both factors should be considered.