TENS, or transcutaneous electrical nerve stimulation, is a well-known safe and effective method for treating many kinds of chronic pain. Two electrodes are attached to the skin to deliver a very low-power electrical stimulation at a very high frequency, or a much stronger electrical shock at a much lower frequency.
Electrical shock has been used for pain relief for centuries. The ancient Greeks would catch electric eels for use in treating chronic pain. American founding father Benjamin Franklin recommended electricity for pain relief, and various kinds of batteries were used for treating pain and cancer in the 1800's. By the 1970's a system of electrodes implanted next to the spinal cord was developed for chronic patients, but the patients were first given a "test shock" to see if they could stand the treatment. Many people stopped having pain just from electrical stimulation to the skin, so Medtronic, maker of the electrodes, developed a portable system that did not require surgery. The system came to be known as TENS.
Some type 2 diabetics with painful neuropathy are completely cured by TENS, and some get no benefit at all. Generally, TENS does more to restore sensation than it does to control stabbing or burning pain. If the method works, however, its benefits last for up to four months after the last treatment, and there are no side effects.
Bosi E, Conti M, Vermigli C, Cazzetta G, Peretti E, Cordoni MC, Galimberti G, Scionti L. Effectiveness of frequency-modulated electromagnetic neural stimulation in the treatment of painful diabetic neuropathy. Diabetologia. 2005 May;48(5):817-23. Epub 2005 Apr 15.
Forst T, Nguyen M, Forst S, Disselhoff B, Pohlmann T, Pfützner A. Impact of low frequency transcutaneous electrical nerve stimulation on symptomatic diabetic neuropathy using the new Salutaris device. Diabetes Nutr Metab. 2004 Jun;17(3):163-8.