Temporal Relationship Between Childhood Body Mass Index and Insulin and Its Impact on Adult Hypertension: The Bogalusa Heart Study

Abstract

Although obesity and insulin resistance are closely correlated, their temporal sequences in early life and influence on adult hypertension are largely unknown. This study aims to delineate the temporal relationship patterns between body mass index (BMI) and insulin in childhood and their impact on adult hypertension. The longitudinal cohort consisted of 990 adults (630 whites and 360 blacks) who had BMI and fasting insulin measured twice 5.4 years apart in childhood (mean age, 10.5 years at baseline and 15.9 years at follow-up) and blood pressure measured 14.7 years later in adulthood (mean age, 30.5 years). Cross-lagged panel and mediation analysis models were used to examine the temporal relationship between childhood BMI and insulin and its impact on adult hypertension. After adjusting for age, race, sex, and follow-up years, the cross-lagged path coefficient (β=0.33; P<0.001) from baseline BMI to follow-up insulin was significantly greater than the path coefficient (β=-0.02; P>0.05) from baseline insulin to follow-up BMI in childhood with P<0.001 for the difference in βs. Blacks and whites showed similar patterns of the temporal relationship. The path coefficient (β=0.59; P<0.001) from BMI to insulin in the hypertensive group was significantly greater than that (β=0.24; P<0.001) in normotensive group, with P<0.001 for the difference in βs between these 2 groups. The mediation effect of childhood insulin on the childhood BMI-adult hypertension association was estimated at 21.1% (P<0.001). These findings provide evidence that higher BMI levels precede hyperinsulinemia during childhood, and this 1-directional relation plays a role in the development of hypertension.

Keywords: blood pressure; body mass index; hyperinsulinism; hypertension; obesity.

Figure 1

Cross-lagged path analysis of childhood BMI and insulin (n=990), adjusted for age, race, gender, and follow-up years β₁, β₂ = cross-lagged path coefficients; r₁ = synchronous correlations; r₂, r₃ = tracking correlations; R² = variance explained Goodness-of-fit: RMR=0.063 and CFI=0.93 Coefficients different from 0: * p<0.01 ^†, p<0.001 for difference between β₁ and β₂

Figure 2

Cross-lagged analysis models of childhood BMI and insulin in normotensive and hypertensive groups, adjusted for age, race, gender, and follow-up years β₁, β₂ = cross-lagged path coefficients; r₁ = synchronous correlations; r₂, r₃ = tracking correlations; R² = variance explained Goodness-of-fit: RMR=0.047 and CFI=0.94 for hypertensives; RMR=0.069 and CFI=0.93 for normotensives; Coefficients different from 0: * p<0.01 ^†, p<0.001 for difference in β₂s between hypertensive and normotensive groups

Figure 3

Mediation effect of childhood insulin on the childhood BMI-adult hypertension association Coefficients different from 0: * p<0.01