Life course path analysis of total and central adiposity throughout adolescence on adult blood pressure and insulin resistance

Background and aim: We aimed to study whether the effect of adolescent adiposity on adult blood pressure and insulin resistance was mediated by adult adiposity. Methods and results: Data from the EPITeen cohort at 13, 17 and 21 years was used (n = 2211). Sex- and age-specific body mass index z-scores (BMIz) and waist-to-hip ratio (WHR) were used as indicators of total and central adiposity, respectively. Systolic blood pressure (SBP), glucose and insulin were assessed at 21 years and the homeostasis model assessment (HOMA-IR) was used as a marker of insulin resistance. Path analysis was applied to evaluate direct and indirect effects of adiposity (13, 17 and 21y) on adult SBP and HOMA-IR, separately for total and central adiposity and for each outcome. Results are presented as standardized regression coefficients [beta (95%CI)]. The total effect of BMIz at 13 years on SBP at 21 years was 0.211 (0.178; 0.244), totally mediated by adult BMIz. Total effect of BMIz 13y on HOMA-IR was 0.248 (0.196; 0.299). Although this effect was mostly mediated by BMIz 21y, an additional direct effect from BMIz 17y was found [beta = -0.240 (-0.315; -0.164)]. Central adiposity was also positively associated with SBP and HOMA-IR at 21 years, and the effect of adolescent WHR was totally mediated by adult WHR for both outcomes. Conclusions: The effect of adolescent adiposity on adult SBP and HOMA-IR was mostly mediated by adult adiposity. However, for HOMA-IR an additional direct effect from total adiposity at 17 years was found. (C) 2017 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.