Moderately obese, insulin-resistant women exhibit abnormal vascular reactivity to stress

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 base-line and during stress included heart rate, blood pressure, cardiac output, and systemic vascular resistance. The IR group weighed more (84 versus 66 ks). 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. Base-line 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 blond 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.