Purpose: To investigate the influence of nerve decompression at potential entrapment sites in the lower extremity in painful diabetic polyneuropathy on nerve conduction study variables. Methods: Forty-two patients with painful diabetic polyneuropathy were included in this prospective randomized controlled trial. Preoperative nerve conduction studies were performed bilaterally. Each patient underwent unilateral surgical decompression of the tibial nerve and common, superficial, and deep peroneal nerves. The contralateral side was used as a control: within-patient comparison. One year postoperatively, the nerve conduction studies were repeated. Univariate paired sample T-tests and a multivariate analysis of variance were performed to compare data. Results: In univariate analysis of the peroneal nerve, the distal compound muscle action potential amplitude measured at the extensor digitorum brevis muscle of the intervention legs decreased significantly, as did the area drop measured at the extensor digitorum brevis muscle of the control legs. The distal motor latency measured at the extensor digitorum brevis muscle of the intervention legs increased significantly, as did the distal compound muscle action potential amplitude measured at the anterior tibial muscle of the control legs. For the tibial nerve, the distal compound muscle action potential duration decreased significantly in the control legs. The multivariate analysis showed no significance overall. Conclusions: Decompression of nerves of the lower extremity in patients with painful diabetic polyneuropathy has no beneficial effect on nerve conduction study variables 12 months after surgery.