Blockade of the renin-angiotensin system increases plasma adiponectin levels in type-2 diabetic patients with proteinuria

Background/Aims: Adiponectin seems to be an important modulator for metabolic and vascular diseases. A case study was designed to measure plasma adiponectin levels and to investigate the effects of angiotensin-converting enzyme inhibitors on adiponectin levels in type-2 diabetic patients with proteinuria. Methods: Forty-nine patients ( 28 males, 21 females) and 23 healthy volunteers ( 13 males, 10 females) were included in the case study. Patients with proteinuria were treated with 5 mg/ day ramipril ( n = 21) for 4 weeks. Results: Adiponectin levels of patients were significantly lower than those of healthy volunteers ( p < 0.001). There were significant negative correlations between adiponectin concentrations and insulin levels as well as the homeostasis model assessment (HOMA) index in the patient group ( r = - 0.655, p < 0.001; r = - 0.469, p = 0.001, respectively). There was also a significant negative correlation between plasma adiponectin concentrations and the degree of proteinuria ( r = - 0.912, p < 0.001). Plasma adiponectin levels in patients with proteinuria (n = 21; 4.81 +/- 3.17 mu g/ml) were significantly lower than those without proteinuria ( n = 28; 10.25 +/- 2.03 mu g/ml; p < 0.001). After the treatment period, adiponectin levels significantly increased ( p < 0.001) and proteinuria, plasma insulin, and HOMA indexes significantly decreased in the treatment group ( p < 0.001, p < 0.001, p = 0.002, respectively). Conclusions: The results suggest that adiponectin is inversely correlated with proteinuria and treatment with ramipril both corrects proteinuria and increases the low adiponectin levels in diabetic patients. Copyright (C) 2005 S. Karger AG, Basel.