Journal of Human Hypertension
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July 2001, Volume 15, Number 7, Pages 481-485
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Original Article
Increased insulin resistance in salt sensitive essential hypertension
V Giner, A Coca and A de la Sierra

Hypertension Unit, Department of Internal Medicine, IDIBAPS (Institut d'Investigacions Biomèdiques August Pi i Sunyer), Hospital Clínic, University of Barcelona, Spain

Correspondence to: Dr V Giner Galvañ, Hypertension Unit. Department of Internal Medicine, Hospital Clínico de Valencia, University of Valencia, Vicente Blasco Ibáñez 10, 04610, Valencia, Spain E-mail: ginervicgal@gva.es

Abstract

Objective: To determine the possible relationship between insulin resistance and salt sensitivity in essential hypertension.

Design and methods: We studied 17 non-obese, essential hypertensive patients (24-h blood pressure: 149 ± 15/94 ± 5 mm Hg) with normal glucose tolerance. Salt sensitivity was diagnosed in the presence of a significant increase (P < 0.05, more than 4 mm Hg) in 24-h mean blood pressure (MBP) when patients switched from a low-salt intake (50 mmol/day of Na+) to a high-salt intake (240 mmol/day of Na+), each period lasting 7 days. The insulin sensitivity index was determined by the euglycaemic hyperinsulinaemic clamp.

Results: Six patients were classified as salt sensitive (24-h MBP increase: 6.2 ± 1.1 mm Hg), and 11 as salt resistant (24-h MBP increase: -1.2 ± 3.8 mm Hg). No significant differences were observed between salt sensitive and salt resistant patients regarding baseline characteristics, fasting serum insulin, fasting serum glucose, glycosilated haemoglobin, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, uric acid and microalbuminuria. Salt sensitive patients exhibited a reduced insulin sensitivity index compared with salt resistant patients (1.7 ± 1.1 vs 3.5 ± 1.2 mg/kg/min; P = 0.009). An inverse relationship (r -0.57; P = 0.016) between the insulin sensitivity index and 24-h MBP increase with high salt intake was found.

Conclusion: Salt sensitive essential hypertensive patients are more insulin resistant than salt resistant patients when both salt sensitivity and insulin resistance are accurately measured. Indirect measures of both insulin and salt sensitivity and/or the presence of modifying factors, such as obesity or glucose intolerance, may account for differences in previous studies.

Journal of Human Hypertension (2001) 15, 481-485

Keywords

insulin resistance; salt sensitivity; essential hypertension; dietary sodium

Received 8 November 2000; revised 10 March 2001; accepted 10 March 2001
July 2001, Volume 15, Number 7, Pages 481-485
Table of contents    Previous  Abstract  Next   Article  PDF