The purpose of this trial is to find out the appropriate way to treat DM patients with critical limb ischemia. This trial includes two parts. Part I focuses on the treatment of femoral arterial lesion and part II focuses on the treatment of below-knee arterial lesion.

The trial includes two parts and here is part I. This part is a multi-center, prospective, randomized, controlled study to compare the therapeutic effect of stent and bypass to chronic long occlusion of the superficial femoral artery in DM patients. Totally 70 patients will be entered into the study. The lesion of the femoral artery should be TASC B、C or D and the patients should suffered ischemic symptom with Rutherford 3-6.The lesion does not extend beyond the aortoiliac artery or blow-knee popliteal artery, with at least 1 vessel infra-popliteal runoff to the foot.

Inclusion Criteria:

• The patients volunteer to join the trial and sign the formal consent.
• The patients are ≥55 year-old and ≤75 year-old.
• The patients suffer from symptomatic leg ischemia with rutherford classification3, 4 , 5 or 6. The presentation is severe intermittent claudication, rest pain, ulcer or gangrene.
• The lesion of the femoral artery should be TASC B、C or D.
• The femoral-popliteal artery has never received bypass or endovascular therapy before.
• No obvious stenosis or occlusion in the aortoiliac artery; or the lesion could be treated simultaneously or has already been cured.
• No obvious stenosis in below-knee popliteal artery; at least 1 vessel infra-popliteal runoff to the foot.
• No surgical contraindications;no infection in operation region.
• Be diagnosed with DM for at least 1 year.

Exclusion Criteria:

• Refuse random treatment.
• Previous operations on the superficial femoral artery.
• Acute lower extremity arterial thrombosis.
• Serious major organ failure.
• Allergic to the contrast agent or has contrast nephropathy.
• No clinical compliance or unfit to join the trial