Retinol-binding protein 4 (RBP4) has been associated with features of the metabolic syndrome and is a new marker under extensive study. This protein secreted by adipocytes and linked to insulin resistance and microvascular complications (renal dysfunction) was investigated in a sample of 165 non-smoking type 2 diabetic patients. RBP4 concentrations were found to be positively associated with creatinine levels and severity of renal dysfunction. Moreover, patients in the top quartile of RBP4 concentrations had a higher odds ratio (4.68; 95% CI: 1.52-14.36, p=0.007) for moderately impaired renal function compared to other quartiles (adjusted for age, gender, and body mass index). However, there was no association between microalbuminuria and RBP4, while RBP4 concentrations were greater in patients with clinical arteriosclerosis. These findings suggest that RBP4, nephropathy, and cardiovascular disease may be linked in type 2 diabetic patients.