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 microg/ml) were significantly lower than those without proteinuria (n = 28; 10.25 +/- 2.03 microg/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.