CIRCULATING ENDOTHELIN-1 IN NON-INSULIN-DEPENDENT DIABETIC-PATIENTS WITH RETINOPATHY

Endothelin-1 (ET-1), a novel 21-aminoacid vasoconstrictive peptide sec reted by endothelial cells, has been thought to play a role in various forms of vascular disease. Diabetes mellitus is well known for its as sociation with microvascular damage. To investigate whether ET-1 level s may be related to microangiopathy in diabetes mellitus, plasma ET-1 levels were measured in two groups of diabetic patients: A) 47 patient s with non-insulin dependent diabetes mellitus (NIDDM) and retinopathy (28 M, 19 F; mean age 60.7 +/- 8.5 yrs) but without nephropathy (micr oalbuminuria < 30 mg/day) and hypertension (SBP<140, DBP<90 mmHg): gro up A was divided in three subgroups based on the severity of retinopat hy: a) 16 with background retinopathy; b) 21 with pre-proliferative re tinopathy; c) 10 with proliferative retinopathy. B) 8 patients with in sulin-dependent diabetes mellitus (IDDM) recently diagnosed (6 M, 2 F; 16.4 +/- 3.8 yrs) without complications. C) 28 healthy subjects (HS) (16 M, 12 F; 47.8 +/- 11.8 yrs) as controls. In the NIDDM group the ET -1 concentration was significantly higher (17.3 +/- 2.4 pg/ml) than bo th in the HS (8 +/- 4.7 pg/ml) and IDDM patients (10.2 +/- 3.7 pg/ml) (p<0.0001). In the subgroups with retinopathy the ET-1 levels were a) 15.1 +/- 4.3 pg/ml; b) 22.2 +/- 6.8 pg/ml and c) 76.6 +/- 5.1 pg/ml. T hese values were significantly elevated as compared to HS (p<0.001; p< 0.0001; p<0.002, respectively), being the highest levels of ET-1 obser ved in the NIDDM patients with pre-proliferative retinopathy. In concl usion our study revealed that the ET-1 concentrations are elevated in NIDDM patients with retinopathy especially in those patients with pre- proliferative retinopathy.