The correlation of plasma and urine endothelin-1 with the severity of nephropathy in Chinese patients with Type 2 diabetes

To assess whether plasma and urinary endothelin-1 (ET-1) values are related to the severity of diabetic nephropathy, we measured plasma and urinary ET-1-like immunoreactivity (ET-1-LI) in 14 healthy subjects, and in 50 normoalbuminuric (group 1), 13 albuminuric (group 2), and 10 renally insufficient (group 3) patients with Type 2 diabetes. Plasma ET-1-LI values were significantly increased in group 3, and correlated positively with serum creatinine levels (r = 0.579, p < 0.01). Urinary ET-1-LI excretion in group 3 (49.3 +/- 7.3 pmol day-1) was significantly higher than that in healthy controls (27.0 +/- 1.1 pmol day-1) and in group 1 (32.2 +/- 2.2 pmol day-1), while that of group 2 (38.8 +/- 5.9 pmol day-1) was also higher than in healthy controls. A significant positive correlation between urinary ET-1-LI and serum creatinine values was also found (r = 0.297, p < 0.05). Trend analysis showed significant linear and quadratic trends in the elevation of plasma ET-1-LI and a significant linear trend in urinary ET-1-LI levels from healthy controls to groups 1, 2 and 3. Our results demonstrate that an increase in plasma and urine ET-1-LI correlates with the severity of diabetic nephropathy.