If you have diabetes, your blood glucose, or blood sugar, levels are too high.  Over time, this can damage the covering on your nerves or the blood vessels that bring oxygen to your nerves. Damaged nerves may stop sending messages, or may send messages slowly or at the wrong times.  
This damage is called diabetic neuropathy.  Over half of people with diabetes get it.  Symptoms may include
	Numbness in your hands, legs, or feet
	Shooting pains, burning, or tingling
	Nausea, vomiting, constipation, or diarrhea
	Problems with sexual function
	Urinary problems
	Dizziness when you change positions quickly
Your doctor will diagnose diabetic neuropathy with a physical exam and nerve tests. Controlling your blood sugar can help prevent nerve problems, or keep them from getting worse. Treatment may include pain relief and other medicines.
  NIH: National Institute of Diabetes and Digestive and Kidney Diseases