Effect of adiponectin on carotid arterial stiffness in type 2 diabetic patients treated with pioglitazone and metformin

Adiponectin, an adipocyte-specific plasma protein, has been reported to exhibit protective effects against atherosclerosis as well as an insulin-sensitizing effect. This study was designed to investigate the effect of adiponectin on carotid arterial stiffness in type 2 diabetic patients treated with pioglitazone and metformin. Twenty type 2 diabetic patients were enrolled and divided into 2 groups, a pioglitazone-treated group (n = 10) and a metformin-treated group (n = 10). Before and after intervention, plasma adiponectin levels were measured by enzyme-linked immunosorbent assay and carotid arterial stiffness was evaluated by the stiffness parameter β, measured by ultrasound equipped with a phase-locked echo-tracking system. In the pioglitazone group, plasma adiponectin level significantly increased and stiffness parameter β significantly decreased, whereas in the metformin group neither of these parameters changed significantly. The changes in stiffness parameter β were significantly and inversely correlated with change in plasma adiponectin level after treatment with pioglitazone or metformin in the group of all subjects (r = −0.472, P = .036). In conclusion, the present study is the first to demonstrate that increase in adiponectin level after treatment with the insulin sensitizers pioglitazone and metformin may improve arterial stiffness in patients with type 2 diabetes mellitus.