If uncontrolled diabetes,TMJ is also an disorder.
Circular Headache: One of the most common symptoms of temporomandibular joint (TMJ) is a headache similar to one that would be felt when a cloth would be tightly tied on the head for a long period of time. Many people who suffer from a headache due to TMJ describe it as a ring of pain around the head. The pain increases every time a TMJ sufferer speaks or grinds his teeth.
The constant contraction of the muscles of the mandibles creates a stress and strain in the face, head and neck. This muscular contraction reduces the amount of blood in the head. The body responds by sending more blood this region which increases the blood pressure in the head region which gives a headache.