Diabetic muscular infarct (DMI) is a rare condition, which begins with acute onset of extremity pain and swelling. Patients usually have long-standing disease and poorly controlled diabetes mellitus (DM). Thigh muscle group is the most commonly involved side, while lower leg involvement is rare. We represent herein a 22-year-old patient with type I DM who admitted to our outpatient clinic due to painful swelling of the left leg. In physical examination, anterior left leg was painful and firm on palpation; there was diffuse swelling extending to the knee and ankle with mild local fever and redness. T2-weighted MRI demonstrated hyperintensity in left leg muscles. A biopsy confirmed the diagnosis of DMI. She was treated with glucose regulation, analgesics, antiplatelet treatment and rest. At her 6 months, recurrence of DMI was observed. DMI should be considered in diabetic patients with extremity pain and swelling. Treatment plan should include the regulation of the blood glucose and evaluation of end-organ complications, analgesia, and bed rest.