Background: Diabetes is associated with increased cardiovascular morbidity and mortality. Endothelial progenitor cells (EPCs) are bone marrow-derived cells involved in endothelial health and vasculogenesis. Both subjects with type 1 and type 2 diabetes (T1D and T2D) showed a lower number of EPCs and impaired EPCs function, compared with age-matched controls. Aim To investigate the difference in diabetes-related clinical variables in patients with T1D by levels of circulating endothelial progenitor cells. Methods: We conducted a single-center observational study on young adults with T1D, treated with multiple daily injections of insulin (MDI) or continuous subcutaneous insulin infusion (CSII) since 6 months. Circulating EPCs levels were assessed by flow cytometry. Participants were divided into two equal groups based on the median absolute level of circulating CD34+ EPCs (Low EPCs and High EPCs group). Results: A total of 130 patients (66 men and 64 women) with T1D (mean age of 23.9 and mean diabetes duration of 14.6) were included. There were no differences in the clinical variables in the group with Low EPCs vs High EPCs except for systolic blood pressure (p<0.001), diastolic blood pressure (p=0.008) and insulin doses (p=0.022) that were lower in the Low EPCs group compared with the High EPCs group. Patients in the High EPCs group had lower HbA1c levels and a higher TIR compared to the group with Low EPCs, although these results were not statistically significant. Furthermore, in the Low EPCs group there was a greater number of women (p<0.001), CSII users (p<0.001) and participants with diabetes-related complications (p=0.009) than High EPCs group; on the other hand, in the High EPCs group we found a greater number of smokers (p=0.957) and a greater number of patients treated with MDI (p<0.001), as compared with the group with Low EPCs. Conclusions: In adults with T1D, EPCs counts do not influence clinical parameters related to diabetes. A lower number of circulating EPCs is associated with female gender and the presence of diabetes complications suggesting that further longitudinal studies are necessary in order to better examine the mechanisms between endothelial health and diabetes mellitus.