Objectives: Endothelial dysfunction contributes to the development of atherosclerosis in diabetic subjects. Endothelin-1 (ET-1) is an endothelium derived vasoconstrictor. It has been shown that ET-1 levels are increased in a variety of situations such as diabetes, hypertension and obesity. Transforming growth factor beta1 (TGF-β1) is an important cytokine for the development of renal injury in type 2 diabetic patients and associated with hyperglycemia and insulin resistance. Cell culture studies showed that TGF-β may upregulate ET-1 production. Our aim was to demonstrate the possible relations between ET-1 and TGF-β1 in type 2 diabetic patients.
Methods: Forty Type 2 diabetic subjects without any micro or macrovascular diabetic complications, hypertension or microalbuminuria were enrolled. The patients were being treated with glimepride for at least 12 weeks. Patients treated with other oral antidiabetics or insulin, anti-hypertensive drugs, anticoagulants or anti-obesity drugs were not included.
Results: The mean values were; A1c: 7.8%, fasting plasma glucose: 167.9 mg/dl, BMI: 27.5 kg/m2, waist circumference: 91.0 cm, TGF-β1: 29.68 ng/ml and ET-1: 0.33 fmol/ml. ET-1 levels were not associated with glycemic parameters or anthropometric features. ET-1 levels did not differ between males and females. ET-1 levels were found to be correlated with TGF-β1 levels (r=0.358 P<0.05).
Conclusion: Our results demonstrate that ET-1 expression is associated with TGF-β1 in type 2 diabetic people. Neither glycemic parameters nor anthropometric features were found to effect ET-1 levels in type 2 diabetic people without diabetes related complications. A possible explanation for this finding may be the strict enrolment criteria for the study. Because of the inclusion of patients without diabetes related complications, ET-1 levels might be found to be unrelated with glycemic parameters.