Diabetes can cause damage to the nerves throughout the body when blood glucose and blood pressure are too high. This is called diabetic neuropathy and can lead to problems with digestion, erectile dysfunction, and many other functions.
Among the most commonly affected areas are the extremities, in particular the feet. Nerve damage in these areas is called peripheral neuropathy, and can lead to pain, tingling, and loss of feeling. Loss of feeling puts your feet at risk of injury and infection, and can lead to gangrene and amputation. To prevent this, check your feet regularly and seek medical attention if there is an ulcer or inflammation, or blisters.
Reference: www.idf.org/aboutdiabetes/complications