Moderately Obese, Insulin-Resistant Women Exhibit Abnormal Vascular Reactivity to Stress

Abstract

Abstract To define the hemodynamic implications of insulin resistance (IR), we compared 10 normotensive, insulin-resistant women who had abnormal glucose tolerance tests with 10 age-matched healthy normotensive women with normal glucose tolerance tests with respect to mental arithmetic and handgrip responses. Hemodynamic variables obtained at baseline and during stress included heart rate, blood pressure, cardiac output, and systemic vascular resistance. The IR group weighed more (84 versus 66 kg). Screening BP was similar (123/72 versus 120/68 mm Hg, P =NS) between groups although baseline diastolic BP at testing day was higher in the IR group than control group (75 versus 65 mm Hg, P <.05). The IR group showed a significantly greater increase in systolic (18% versus 10%, P <.01) and diastolic (24% versus 12%, P <.01) blood pressure responses to mental stress than the control group. During mental stress, the control group demonstrated increased cardiac output (1.4 L/min) and decreased systemic vascular resistance (−120 dyne · s · cm −5 ), whereas IR subjects demonstrated increased systemic vascular resistance (119 dyne · s · cm −5 ; group difference, P <.02) with only a small increase in cardiac output (0.5 L/min). Handgrip also caused a greater increase in systemic vascular resistance in the IR group (252 versus 64 dyne · s · cm −5 , P <.05), with a correspondingly greater increase in blood pressure than control subjects. Baseline blood pressure was correlated with weight ( r =.41, P <.02) and stress blood pressure with fasting insulin ( r =.51, P <.001) and glucose-to-insulin ratio ( r =−.55, P <.001). We conclude that insulin resistance is associated with an exaggerated blood pressure response to stress; an enhanced vasoconstriction to stress may mediate this response. This hyperreactivity may be a marker for future hypertension in obese, normotensive, hyperinsulinemic individuals.