Plasma and aqueous humor endothelin-1 levels in patients with non-insulin-dependent diabetes mellitus with and without retinopathy

The purpose of this study was to investigate the role of endothelin-1 (ET-1) in the pathogenesis of diabetic retinopathy. We examined (by enzyme-linked immunosorbent assay) ET-I plasma and aqueous humor levels in 20 patients with noninsulin-dependent diabetes mellitus (NIDDM) and in 13 control subjects. Plasma ET-I levels (mean +/- standard deviation) were 0.901 +/- 0.508 pg/mL in diabetic patients without retinopathy, 1.116 +/- 0.243 pg/mL in patients with nonproliferative diabetic retinopathy, and 1.045 +/- 0.430 pg/mL in patients with proliferative diabetic retinopathy (PDR), which were not significantly different from those of the control subjects (0.771 +/- 0.404 pg/mL, P > 0.05). Aqueous humor ET-1 levels were 2.535 +/- 0.988 pg/mL in diabetic patients without retinopathy, 3.646 +/- 0.835 pg/mL in patients with nonproliferative retinopathy, and 6.818 +/- 3.502 pg/mL in patients with PDR, which were significantly different to those of controls (0.303 +/- 0.287 pg/mL, P < 0.05). ET-1 is elevated in the aqueous humor of diabetic patients, more significantly in those with PDR, suggesting that it may be involved in the pathogenesis of diabetic retinopathy.