Stress-induced hemodynamic responses are associated with insulin resistance in mild hypertensives.

BACKGROUND High blood pressure (BP) and pulse pressure (PP) are recognized as independent risk factors for cardiovascular diseases, whereas insulin resistance (IR) is often associated with hypertension. The purpose of the study was to verify whether PP, taken at the doctor's office and during laboratory stimuli, might be predictive of IR. METHODS Homeostasis model assessment insulin resistance index (HOMA) was calculated in 75 grade 1 hypertensives (148 +/- 2/92 +/- 1 mm Hg). Then, patients underwent hemodynamic reactivity study, induced by color word stroop, cold pressor, and handgrip tests. Stress response was calculated as total area (value x time) - baseline area (baseline value x time). RESULTS Patients with similar age, history of hypertension, blood lipids and office blood pressure, but different HOMA (IR-low: 36.3 +/- 1.7 v IR-medium: 62.6 +/- 1.6, P <.001; IR-high: 123.1 +/- 12.8, P <.001 v IR-low and IR-medium), were divided in tertiles. They demonstrated a significant reactivity of systolic BP (IR-low: 225 +/- 58 v IR-medium: 448 +/- 43, P <.01; IR-high: 625 +/- 55, P <.001 v IR-low and P <.01 v IR-medium), PP (IR-low: -8 +/- 19 v IR-medium: 83 +/- 13, P <.001; IR-high: 201 +/- 19, P <.001 v IR-low and IR-medium), and stroke volume (SV) (IR-low: -138 +/- 43 v IR-medium: 1 +/- 27, P <.01; IR-high: 28 +/- 24, P <.001 v IR-low), but similar arterial stiffness (PP/SV) response. Partial correlation between IR and hemodynamic measurements showed a significant association only for systolic BP (0.54, P <.001), PP (0.686, P <.001), and SV (0.384, P <.001) reactivity, but not for office and baseline values. Stepwise multiple regression showed that only PP (beta: 0.634, P <.001) and, among hemodynamic determinants, SV (beta: 0.401, P <.001) response entered into the equation. CONCLUSIONS The findings demonstrate that increased stress-induced PP, maintained by SV response, is the most predictive hemodynamic variable of reduced insulin sensitivity in mild hypertensives.