If you have diabetes, your blood glucose, or blood sugar, levels are too high. Over time, this can damage your nerves or blood vessels. Nerve damage from diabetes can cause you to lose feeling in your feet. You may not feel a cut, a blister or a sore. Foot injuries such as these can cause ulcers and infections. Serious cases may even lead to amputation. Damage to the blood vessels can also mean that your feet do not get enough blood and oxygen. It is harder for your foot to heal if you do get a sore or infection.