Hyperinsulinemia and blood pressure sensitivity to sodium in young blacks

The relationship of blood pressure sensitivity to sodium with plasma insulin concentration was examined in young adult (22 to 28 yr) blacks (N = 45). The study included normotensive and borderline hypertensive subjects. Blood pressure sensitivity to sodium was determined by the change in mean blood pressure after 14 days of sodium loading (10 g of NaCl daily plus usual diet). Plasma insulin concentration was determined during an oral glucose tolerance test (OGTT). The correlation of fasting plasma insulin concentration with blood pressure or blood pressure sensitivity to sodium was not statistically significant. There was a significant correlation (after adjustment for adiposity) of blood pressure sensitivity to sodium with both the sum of insulin (r = 0.41; P < 0.01) and the 60-min plasma insulin concentration during the OGTT. The plasma insulin concentration at 60 min during the OGTT correlated significantly with the change in mean arterial pressure over a 5-yr interval (r = 0.36; P < 0.02). There was a similar significant correlation of blood pressure sensitivity to sodium with change in mean arterial pressure over 5 yr (r = 0.48; P < 0.001). These data demonstrate an association of hyperinsulinemia and blood pressure sensitivity to sodium in the young. The data also suggest that insulin may contribute to the pathogenesis of hypertension in the black population.