Diabetic muscle infarction (DMI) is a rare complication of long-standing diabetes mellitus. This is the first case of DMI reported by cardiologists. A 49-year-old patient with a history of diabetes and hypertension for only two years was admitted to the cardiac ward due to pain in the left thigh with pitting edema in both lower extremities. Magnetic resonance imaging finally confirmed the presence of DMI in the left thigh, which was improved by treatment with anticoagulants, analgesics and rest. However, the typical clinical symptoms of DMI were unrecognizable at the start of treatment, which may be attributed to a lack of awareness of this rare condition among non-endocrinologist physicians.