Diabete animal studies demonstrated a longer period recovery after local anesthetic injection (perineural administration). No clinical study demonstrated a prolonged nerve block duration in diabete type 2 patients after peripheral nerve block. The investigators hypothesized that block recovery is delayed in diabetic patients.

For diabetic patients, peripheral nerve block is an interesting alternative to general anesthesia because it provides effective analgesia and may decrease haemodynamic complication. The fear of nerve injury after regional anaesthesia in diabetic patients is a concern that has neither been confirmed nor refuted by current literature. As a matter of fact, diabetic patients with neuropathy may be considered at increased risk because of the possibility for double crush syndrome when a chronic axon lesion related to diabetes is associated with an unexpected distal nerve injury related to regional anaesthesia.

Inclusion Criteria:

• age (50 80 yrs) with monofilament test 10 g (> 4/8)

Exclusion Criteria:

• refusal of sciatic nerve block,
• age < 50 yr or > 80 yr,
• American Society of Anesthesiologists state > IV,
• presence of contraindications to local anaesthesia (known allergy to local anaesthetics, sepsis),
• emergency surgery,
• patients unlikely to be fully cooperative during the study,
• psychiatric disorders, or
• those abusing alcohol or drugs, and
• participation in another study within the previous 30 days. Moreover, patients with preoperative estimated values of creatinine clearance < 50 mL min-1 (Cockroft and Gault Formula) or with glycosylated hemoglobin (A1c) level > 8 % or with type 1 diabetes mellitus (insulin therapy)