Diabetic muscle infarction, also known as diabetic myonecrosis, is a microvascular complication of poorly controlled diabetes mellitus characterized by unilateral limb pain and swelling. Because these symptoms closely mimic cellulitis and thromboembolism, diagnosis is often delayed or missed altogether, leading to increased morbidity and inappropriate treatment. We describe a case of unilateral limb pain and swelling due to diabetic muscle infarction in a 36-year-old patient with poorly controlled diabetes mellitus. We also review the literature on the diagnosis, prognosis, and management of this underrecognized condition.