Troglitazone-induced changes in adiponectin do not affect endothelial function in diabetes

Abstract

Objective: Adiponectin has been proposed to be related to endothelial function. We have examined the relationship between the increase in adiponectin levels that is associated with troglitazone treatment and endothelium-dependent vasodilation in type 2 diabetic patients. Research Methods and Procedures: Seventy-two patients participated in this randomized, placebo-controlled, double-blinded study. High-resolution ultrasound images were used to measure the flow-mediated dilation (endothelium-dependent) and nitroglycerin-induced dilation (endothelium-independent) of the brachial artery. Laser Doppler perfusion imaging was employed to measure the vascular reactivity in the forearm skin. Results: Troglitazone treatment resulted in an average 75% increase in the adiponectin levels, but no changes were observed in the endothelium- dependent vasodilation, any other measurement of vascular reactivity, or any other markers of endothelial activation. Also, no changes were observed in the expression of the receptor for advanced glycation end-products in skin biopsies taken from the forearm. Significant correlations were observed during troglitazone treatment between the changes in the adiponectin levels and the changes in fasting plasma glucose (r = -0.29, p < 0.05), hemoglobin A 1c (r = -0.30, p < 0.05), total cholesterol (r = 0.25, p < 0.05), and low-density lipoprotein-cholesterol (r = 0.34, p < 0.01). Discussion: The increase in adiponectin levels after troglitazone treatment is not associated with an improvement in the endothelium-dependent vasodilation, indicating that adiponectin is not a major determinant of endothelial function. In addition, receptor for advanced glycation end-products expression in the skin microcirculation is not affected by troglitazone treatment. Copyright © 2005 NAASO.