The patient was an 86-year-old woman and a former war-displaced orphan with limited proficiency in Japanese. She resided in a care facility and independently managed her basic activities of daily living. She had been diagnosed with type 2 diabetes mellitus 3 years earlier, maintaining HbA1c levels around 7.0% through dietary and exercise therapy. Her relatives regularly provided her with sweets and beverages. Oral prednisolone 7.5 mg had been initiated 28 days prior to admission for dermatitis and was tapered to 5 mg 14 days earlier. Two days before admission, she experienced a loss of appetite, and on the day of admission, she presented to the emergency department with choreiform movements of the left upper and lower limbs. Brain magnetic resonance imaging revealed no abnormalities associated with the involuntary movements. Random blood glucose was 802 mg/dL. She was hospitalized and treated with insulin, achieving glycemic control. Insulin therapy was discontinued, and she was discharged on day 8 with oral hypoglycemic agents. Potential mechanisms of chorea included diabetic chorea and cerebral ischemia. While steroid-induced glucose intolerance is typically associated with high doses or prolonged use, this case highlights that even low-dose, short-term steroid therapy can impair glucose tolerance, particularly in elderly patients, necessitating greater caution.