We present a 58-year-old man with hyperglycemic subcoma. His blood glucose level was 1,163 mg/100 ml on admission and the data of the coagulate system revealed abnormalities in the prothrombin time, fibrinogen and serum fibrin degradation products. Continuous intravenous insulin infusion therapy (CIII) was performed, and a satisfactory recovery of consciousness level and blood glucose level were obtained. Further examination revealed the patient had Crohn's disease (CD) associated with IgG and IgM anticardiolipin antibodies (aCLs). The patient was treated with corticosteroid hormones and salazosulfapyridine, and the abnormalities in the coagulate system returned to the normal range and aCLs eventually disappeared. It was speculated that in such a case, anticardiolipin antibody may play a role in the pathogenesis of CD.