Many reports indicate a hypercoagulative state in diabetes mellitus as result of endothelial damage. Experimental evidence suggests that a metabolic derangement triggers a cascade of biochemical events that lead to vascular dysfunction. The net effect is to convert the endothelium from thromboresistant to thrombogenic surface. In literature, a strong association between type 1 diabetes mellitus (DM1) and celiac disease (CD) has been reported. We do not have information about the hemostatic system in these associated conditions. Our study aims at evaluating whether the presence of CD in a group of DM1 patients is associated with a different expression of some hemostatic factors and with a different manifestation and/or progression of microvascular complications of DM1 in comparison with patients with only diabetes. Ninety-four adult DM1 patients were enrolled in the study and subsequently screened for CD. Anti-endomysial antibodies (EMA) were positive in 13 of 94 DM1 patients (13.8%). CD diagnosis was confirmed by histology and organ culture. The mean age and duration of DM1 of patients also affected by CD were similar to those of only diabetic patients, but the metabolic control and the hemocoagulative parameters were significantly different between the two groups: DM1 patients also affected by CD presented significantly lower concentrations of glycosylated hemoglobin (HbA1c) (P < 0.05), cholesterol (P < 0.001), triglycerides (P < 0.001), factor VII antigen (FVII:ag) (P < 0.005), factor VII coagulant activity (FVII:c) (P < 0.05), and prothrombin degradation fragments (F1+2) (P < 0.001), as well as higher values of activated C protein (APC) (<0.001). No retinal abnormalities and no signs of renal damage were observed in DM1 patients also affected by CD. Our results suggest a potential protective role of CD in the prothrombotic state of DM1.