IMPAIRED INSULIN SENSITIVITY AND MAXIMAL RESPONSIVENESS IN OLDER HYPERTENSIVE MEN

This study examines the relation between blood pressure and insulin resistance in obese, sedentary middle-aged and older men. Eleven hypertensive and 17 normotensive subjects of comparable age (58.6+/-1.0 years, mean+/-SEM), percent body fat (27.7+/-0.7%), and maximal aerobic capacity (30.2+/-0.9 mL.kg(-1) min(-1)) participated in this study. Glucose disposal (M, milligrams per kilogram of fat-flee mass per minute) determined during a three-dose hyperinsulinemic euglycemic clamp was lower in the hypertensive than normotensive subjects at the low (M at 120 pmol/m(2).min: 2.3+/-0.2 versus 3.2+/-0.3, P=.06), intermediate (M at 600 pmol/m(2) min: 8.0+/-0.6 versus 10.4+/-0.6, P=.02), and high (M at 3000 pmol/m(2) min: 13.5+/-0.5 versus 15.5+/-0.7, P=.04) insulin infusion rates. The calculated insulin concentration necessary for a half-maximal effect (EC(50)) was greater in the hypertensive than normotensive subjects (1164+/-168 versus 864+/-66 pmol/L, P=.03). In this population of normotensive and hypertensive men, systolic, diastolic, and mean arterial blood pressures were related to glucose disposal at these insulin infusion rates (r=-.35 to -.46, P<.05) as well as the EC(50) (r=.42 to .44, P<.05). Thus, hypertensive obese, sedentary older men have a reduction in both sensitivity and maximal responsiveness to insulin that is directly related to the severity of hypertension independent of obesity and physical fitness.