Influence of cholesterol and fasting insulin levels on blood pressure reactivity

Objective: This study examined how cholesterol and fasting insulin levels are related to blood pressure reactivity to behavioral stressors. Methods: Subjects (N = 116) were 20 to 52 years old, at 80% to 150% of ideal weight, and had an average fasting cholesterol level of 183 mg/dl. Stressor tasks included mirror star tracing and a videotaped speech task. Changes from baseline were calculated for systolic and diastolic blood pressure. Results: Neither cholesterol nor insulin was independently related to blood pressure change scores. However, after controlling for body mass, a two-way analysis of variance revealed a significant cholesterol-by-insulin interaction for change in diastolic blood pressure (p = .022). Subjects in the high-cholesterol/high-insulin group showed the greatest increase in diastolic blood pressure reactivity. Conclusions: In a general population, people with a below-average cholesterol level experience only moderate cardiovascular reactivity to mental stressors regardless of their fasting insulin level. However, for people with an above-average cholesterol level, fasting insulin level is an important factor in determining potential reactivity to mental stressors. These findings highlight the importance of adequate sample size to allow for the analysis of such interactions in future studies of cholesterol, insulin, and blood pressure reactivity.