Abstract A 67-year-old woman with diabetes mellitus was hospitalized due to a throbbing headache. She appeared neurologically normal, except for meningeal irritation. The cerebrospinal fluid pressure was high. There was increased fluid protein without an increased cell count. Brain CT scan showed no abnormality, however, brain magnetic resonance angiography (MRA) showed complete right transverse sinus stasis and partial left transverse sinus stasis, indicating bilateral transverse sinus thrombosis. At this time thrombin anti-thrombin III complex (TAT) and prothrombin fragment F1+2 (PTF1+2) indicating hypercoagulation had increased. Urokinase, followed by aspirin and ticlopidine hydrochloride were administered. After diet therapy and transient insulin administration, her blood glucose levels improved. By the 22nd day, the headache had disappeared. Subsequently, brain MRA showed left transverse sinus blood flow recovery and complete right transverse sinus stasis, while carotid angiography showed recovered left transverse sinus but right transverse sinus defect. TAT and PTF1+2 levels improved concomitantly with better blood glucose control. We diagnosed this case as left transverse sinus thrombosis because of the hypercoagulable state resulting from diabetes mellitus accompanied by right transverse sinus aplasia.