Body mass index, leptin, and ambulatory blood pressure variability in healthy adults.

Objective: To investigate the association between body mass index (BMI) and 24-h ambulatory blood pressure (ABP) variability, and to assess whether leptin might act as a mediator of this association.

Methods: A cross-sectional study in healthy, normotensive men and women (n = 156). BMI was derived from direct height and weight measurements made on each participant. All participants underwent 24-h ABP monitoring, and two measures of ABP variability were derived--the weighted standard deviation (wSD) and the average real variability (ARV). Plasma leptin was measured using an enzyme lined immunosorbant assay.

Results: In linear regression models adjusted for demographic factors, glucose, creatinine, lipids, and mean ABP, BMI showed positive and statistically significant associations with diastolic wSD, and systolic and diastolic ARV. For those in the low, intermediate, and high BMI groups, mean values for diastolic wSD were 7.7, 7.9, and 8.5 mmHg, respectively (p = .02); mean values of systolic ARV were 8.2, 8.2, and 9.0 mmHg, respectively (p=.02); and mean values of diastolic ARV were 6.7, 7.0, and 7.5 mmHg, respectively (p = .01). Similarly, leptin showed positive and statistically significant associations with measures of wSD and ARV. When BMI was entered as an ordinal variable in regression models for wSD and ARV, adjustment for leptin attenuated significant ordinal BMI coefficients by as much as 60%, suggesting a mediating role for leptin.

Conclusion: In healthy adults, BMI and leptin show positive associations with ABP variability, and leptin may play a mediating role in this association.