NACL SENSITIVITY OF ESSENTIAL HYPERTENSIVE PATIENTS IS RELATED TO INSULIN-RESISTANCE

Objective To evaluate insulin sensitivity of essential hypertensive pa tients with different salt sensitivities of blood pressure in the abse nce of confounding factors such as obesity, glucose intolerance and th e inclusion both of normotensive and of hypertensive subjects that hav e affected most previous studies. Patients Ninety-nine patients with u ntreated mild or moderate essential hypertension, World Health Organiz ation class I-II, participated in the study. Methods Salt sensitivity was estimated using the Weinberger protocol with minor modifications a nd the patients were classified into tertiles of salt sensitivity. Res ults Patients with high NaCl sensitivities were slightly older and had somewhat higher blood pressures than did subjects with low salt sensi tivities. Plasma renin activity significantly decreased with increasin g salt sensitivity. There were no differences among the three groups i n terms of body mass index, fasting blood glucose and insulin plasma l evels. There were no differences among the groups in the integrated gl ucose and insulin response to a standard oral-glucose tolerance test. However, there was a significant difference in insulin sensitivity bet ween two subgroups of the upper and lower tertile of salt sensitivity, the salt-sensitive hypertensives having a markedly lower utilization of glucose than did the salt-resistant ones, with a minor overlap (5.4 +/- 0.6 versus 7.4 +/- 0.3 mg/kg per min, P < 0.01). Conclusions This study showed that essential hypertensive patients with high NaCl sens itivities were relatively insulin resistant compared with those with l ow NaCl sensitivities, independently of confounding factors such as ag e, obesity and glucose intolerance. Insulin resistance was not associa ted with overt hyperinsulinaemia among these patients.