We evaluated the possible relation between plasma endothelin-1 (ET-I) levels and metabolic control, risk factors, treatment modalities, and diabetic microangiopathy, including nephropathy, neuropathy, and retinopathy in patients with Type 2 diabetes and healthy control group. Sixty-eight (39 females and 29 males) patients with Type 2 diabetes and 14 (6 females and 8 males) healthy subjects were included in the study. Plasma ET-I levels were found to be 10.46 +/- 1.24 pmol/l in the diabetic group, whereas 7.97 +/- 0.41 pmol/l in the control group, which was statistically significant (P < .01). We also found elevated plasma ET-I levels in patients with the least one microvascular complication when compared with the uncomplicated diabetes group (P=.02). Moreover, plasma ET-1 levels of the uncomplicated group was higher than the control group (P < .05). Plasma ET-1 levels were significantly elevated in hypertensive diabetics than normotensive diabetics (t=2.58, P=.012). It wets also found to be elevated in diabetic patients with diabetes duration of more than 10 years when compared with patients less than 10 years ( P=.02). These findings can be interpreted as the increased damage of microvascular complications in the disease process that may lead to elevated ET-I levels. Mean plasma ET-I levels in diabetic patients with a family history of diabetes was found to be higher than patients with no family history of diabetes. Genetical and environmental factors may have an effect on ET-1 level. We also studied the correlations of plasma ET-I levels on age, sex, fasting blood glucose levels, treatment modalities HbAlc, hyperlipidemia, C-peptide, Body Mass Index, and smoking, but did not find any statistically significant difference. In conclusion, plasma ET-1 levels are well correlated with microangiopathy, hypertension, increased disease duration, and family history of diabetes, but poorly correlated with metabolic control, treatment modalities, age, sex, hyperlipidemia, obesity, and smoking. (C) 2001 Elsevier Science Inc. All rights reserved.