Bidirectional temporal relationship between obesity and hyperinsulinemia: longitudinal observation from a Chinese cohort

INTRODUCTION: Although obesity and hyperinsulinemia are closely intercorrelated, their temporal sequence is still uncertain. This study aims to investigate the temporal relationship patterns between obesity measures and hyperinsulinemia in Chinese adults. RESEARCH DESIGN AND METHODS: The longitudinal cohort consisted of 2493 participants (860 males and 1633 female, mean age 56.71 years at follow-up) for whom measurements of obesity and hyperinsulinemia measures were collected twice between 2011 and 2014, with an average follow-up time of 3 years. Cross-lagged panel analysis was used to examine the temporal relationship between obesity measures (body mass index (BMI); waist circumference (WC); hip circumference (HC); waist-to-hip ratio (WHR)) and hyperinsulinemia (insulin, homeostasis model assessment of insulin resistance (HOMA-IR), or homeostasis model assessment of beta cell function (HOMA-%β)). RESULTS: After the adjustment of age, sex, smoking, drinking and follow-up years, in the BMI-insulin model, the path coefficient (β(2)=0.229; p<0.001) of baseline BMI to follow-up insulin was significantly greater than the path coefficient (β(1)=0.073; p<0.001) of baseline insulin to follow-up BMI (p<0.001 for β(2)>β(1)). In the WHR-insulin model, the path coefficient (β(1)=0.152; p<0.001) of baseline insulin to follow-up WHR was significantly greater than the path coefficient (β(2)=0.077; p<0.001) of baseline WHR to follow-up insulin (p=0.007 for β(1)>β(2)). In the WC/HC-insulin model, the path coefficients of baseline insulin to follow-up WC or HC (β(1s)) were also greater than the path coefficients of baseline WC or HC to follow-up insulin (β(2s)), but the difference between β(1s) and β(2s) were not significant. The similar temporal patterns were founded between obesity measures with HOMA-IR or HOMA-%β. CONCLUSIONS: These findings indicate that there is a bidirectional relationship between obesity and hyperinsulinemia, and abdominal obesity measures are more sensitive to hyperinsulinemia measures than BMI.