Normally, the muscles in the wall of the stomach contract in a coordinated way to move
food through the stomach into the small intestine. The autonomic nervous system controls this muscular action. Diabetes can damage the autonomic nerves. This is called diabetic autonomic neuropathy. As a result, the stomach loses it's coordinated muscular activity and doesn't empty the stomach properly.
Symptoms can include pain, nausea, vomiting, heartburn and an early fullness when eating.