Elevated plasma endothelin-1 levels in diabetes mellitus

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.