Hypertension and hyperinsulinaemia: a relation in diabetes but not essential hypertension.

To investigate the hypothesis that insulin resistance is concerned in the pathogenesis of essential hypertension fasting glucose/insulin and fasting insulin/C-peptide ratios were measured in non-obese normotensive and hypertensive diabetic and non-diabetic subjects. Patients with essential hypertension had normal fasting serum insulin values and normal fasting glucose/insulin ratios; by contrast, the hypertensive non-insulin-dependent diabetic subjects had higher fasting serum insulin and lower glucose/insulin ratios than either normotensive diabetic or non-diabetic patients. Both hypertensive and normotensive diabetic subjects had higher fasting C-peptide values than those without diabetes. Hypertensive diabetic patients had the highest insulin/C-peptide ratios, indicating low hepatic insulin extraction rates. These findings suggest that hyperinsulinaemia is not causally related to essential hypertension but that it may contribute to the hypertension of non-insulin-dependent diabetes in association with low hepatic insulin clearance.