Interaction between salt intake and glucose metabolism in salt-sensitive hypertensives

Abnormalities in glucose metabolism have been reported in salt-sensitive normotensive and hypertensive subjects. In this study, employing the insulin sensitivity test, also known as insulin suppression test (IST), we investigated the existence of abnormalities in insulin-mediated glucose disposal in salt-sensitive hypertensives, compared to salt-resistant hypertensives. Nonobese, nondiabetic, untreated patients with uncomplicated, mild to moderate essential hypertension were studied. The BP response to low and high salt intake allowed the classification of the patients as salt-sensitive and salt-resistant. No significant differences in fasting morning serum glucose levels were observed between salt-sensitive and salt-resistant hypertensives. However, insulin-mediated glucose disposal was greatly impaired in salt-sensitive subjects. In addition, high salt intake induced fasting hyperinsulinemia and further impaired insulin-mediated glucose disposal assessed by the IST. This effect of high salt was seen in salt-sensitive, but not in salt-resistant patients. These results suggest the existence of a state of insulin resistance in salt-sensitive hypertensives. Salt sensitivity and insulin resistance could be genetically associated conditions, and may represent additional risk factors in the development of cardiovascular disease in essential hypertensives. Salt-sensitive hypertensives may be prone to accelerated cardiovascular complications, experiencing higher BP and worsening of insulin resistance during uncontrolled high salt intake.