[en] We describe the distinctive brain CT and MRI findings seen in the putamen of three patients with hyperglycemia. The chief complaint of these patients was either chorea (n=3D1) or mental change (n=3D2). They showed hyperglycemia, but physical examination and laboratory data revealed no other abnormalities. In all patients, non-enhanced CT scanning revealed high-attenuated lesions in the unilateral putamen. In two of the three patients, brain MRI performed two days after the onset of symptoms showed an abnormally high signal on T1-weighted images and a low signal on T2-weighted images. One patient had a history of diabetes mellitus, and another had acute myocardiac infarction. The third had no specific history. After the correction of hyperglycemia, the patient's symptoms subsided and diabetes mellitus was diagnosed. (author)