Endothelial colony forming cells (ECFCs) derived from peripheral blood have been shown to retain disease phenotype in several conditions thus possessing great translational potential for regenerative medicine. Hyperglycaemia may alter the phenotype of ECFCs yet the characteristics of ECFCs isolated from people with type 1 diabetes (T1D) have not been described. Here, we establish whether ECFCs can be successfully isolated from donors with T1D and we characterize their functional properties. Human ECFCs were isolated from peripheral blood of up to 9 control and T1D donors. Expression of cell markers and cytokines was analyzed using immunocytochemistry, RT-PCR and ELISA. Ca2+ signaling and contraction were studied using Fluo-4-AM in cells treated with serial concentrations of histamine (1 × 10−7-1 × 10−4M). T1D ECFCs showed robust endothelial marker expression and displayed normal morphology but had a reduced size compared to those from control donors. In response to inflammatory stimuli, T1D ECFCs exhibited exaggerated pro-atherogenic/pro-inflammatory cytokine (IL-6 and MCP-1) and adhesion molecule gene induction (VCAM-1 and ICAM-1) but suppressed induction of interferon signaling markers (IP-10). Histamine stimulated a concentration-dependent increase in Ca2+ influx in ECFCs which was significantly reduced in ECFCs from T1D donors, independent of differences in H1 receptor expression levels. Histamine-induced contraction was significantly enhanced in T1D ECFCs. ECFCs from control and T1D donors exhibit distinct phenotypic differences redolent of the vascular pathologies associated with T1D. This establishes the utility of T1D ECFCs for modeling vascular complications but also highlights the need to understand the potential limitations of autologous ECFCs to treat diabetic complications.