Aims/hypothesis: Low serum adiponectin (ADPN) has been associated with increased risk of cardiovascular disease (CVD) and retinopathy in patients with type 2 diabetes mellitus. In type 1 diabetic patients, the relationship between ADPN and the presence of vascular complications is largely unknown. Methods: We investigated the relationship between serum ADPN and the presence of retinopathy, nephropathy and CVD in patients with type 1 diabetes, divided into matched groups with normoalbuminuria and no retinopathy (n=67), simplex retinopathy (n=106) or proliferative retinopathy (n=19), and nephropathy with simplex (n=62) or proliferative retinopathy (n=137). Healthy control subjects (n=25) were included. Results: Serum ADPN was increased in subjects with type 1 diabetes compared with control subjects (p<0.0001). Further, serum ADPN was higher in patients with than in those without nephropathy (p<0.0001). It was also higher in normoalbuminuric patients with than in those without proliferative retinopathy (p<0.0001). These differences remained significant after adjustment for known risk factors (p<0.03). CVD was also associated with elevated ADPN levels (p<0.05), but this difference became insignificant after risk factor adjustment. The most important predictor of serum ADPN was sex (r 2=19%) in normoalbuminuric patients and GFR in patients with nephropathy (r 2=18%). Conclusion/interpretation: Patients with type 1 diabetes and microvascular complications have higher serum levels of ADPN than patients without complications. It remains to be clarified whether elevated levels of ADPN are pathogenically related to the development of microvascular complications or represent a beneficial counter-regulatory response.