Contents Diabetic amyotrophy typically occurs in patients with type 2 diabetes that has been recently diagnosed or under fairly good control. Its cause is considered as ischemic injury from a nonsystemic microvasculitis. Clinical features are acute, asymmetric, focal onset of pain followed by weakness involving the proximal leg, with associated autonomic failure and weight loss. The symptoms and signs progress to affect the contralateral limb and the distal legs, and in part, upper limb and thoracic involvement is observed. A 71-years-old man was admitted with pain and weakness of right hip and thigh. He had difficulty to go to bathroom alone for 3 months and weight loss of 15 kg/ 7 months. He was diagnosed with diabetes 40 years ago and arbitrarily stopped oral anti-diabetic agents 7 months ago. Height was 168 cm and body weight was 52 kg. Right thigh circumference was 35 cm and left thigh circumference was 37 cm at 15cm above knee. Laboratory findings showed Hb 14.3 g/dL, AST 15U/L, ALT 10U/L, total cholesterol 169 mg/dL, triglyceride 178 mg/dL, HDL 34 mg/dL, LDL 110 mg/dL, TSH 1.10 mIU/L, fT4 1.37 ng/dL, C-peptide 1.72 ng/mL, AFP 1.96 ng/mL, CEA 1.84 ng/mL, CA 19~9 7.19 U/mL, BUN 18 mg/dL, Cr 1.08 mg/dL, Na 138mEq/L, K 5.2mEq/L, Cl 102 mEq/L, CRP 0.04 mg/dL, urine ACR 0.285, and HbA1c 10.7%. He had moderate NPDR. Brain and L-spine MRI didn't reveal any abnormal findings suggesting etiologies of patient’s symptoms and signs. Nerve conduction study was consistent with a sensorimoter polyneuropathy and EMG was consistent with L-spine polyradiculopathy. We report a case of diabetic amyotrophy occurred in patient with long duration of diabetes and poor glycemic control.