¹Department of Internal Medicine I, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany

Correspondence: , Department of Internal Medicine I, Endocrinology and Metabolism, University of Heidelberg, Bergheimer Strasse 58, D-69115 Heidelberg, Germany. E-mail: christian_kasperk@med.uni-heidelberg.de

^*This study was supported by grants from the Deutsche Forschungsgemeinschaft DFG (Ka 682/2-3, Ka 682/7-1).

Received 17 April 2002; Accepted 9 July 2002.

Abstract

Background: This study compares plasma endothelin-1 (ET-1) levels in patients with diabetes mellitus or hypertension with healthy controls, and investigates whether ET-1 levels are correlated with glycemic control, metabolic parameters, and vascular complications.

Methods: The study population consisted of 103 patients with type 1 diabetes, 124 patients with type 2 diabetes, 35 hypertensive patients without diabetes mellitus, and 99 controls.

Results: Plasma ET-1 concentrations were significantly higher in patients with type 1 diabetes (0.28 0.34 fmol/mL, P = .001), type 2 diabetes (0.31 0.32 fmol/mL, P < .0001), and hypertension (0.35 0.26 fmol/mL, P < .0001) compared to controls (0.08 0.13 fmol/mL). Diabetic patients taking angiotensin converting enzyme (ACE) inhibitors had significantly lower plasma ET-1 levels than patients without (0.22 0.20 fmol/mL v 0.38 0.39 fmol/mL, P = .029). There were significant associations between ET-1 levels and age (r = 0.38, P < .05) and systolic blood pressure (BP) (r = 0.27, P < .05) in healthy controls. In diabetes we found only nonsignificant associations between ET-1 levels and age or vascular complications and a weak association between plasma ET-1 levels and glycemic control.

Conclusions: Patients with diabetes or hypertension have elevated ET-1 levels, but do not exhibit positive correlations between ET-1 levels and BP, which was observed in healthy controls. Increased ET-1 levels do not induce hypertension in diabetes, but were lower in diabetic patients taking ACE inhibitors compared to those without ACE inhibitors. There is no significant association between ET-1 levels and vascular complications. These findings suggest that the plasma ET-1 level is not a marker of endothelial dysfunction but changes in plasma ET-1 levels may precede vascular complications associated with hypertension and diabetes.