The New York University Langone Medical Center, on the other hand, reports no marked increase in blood sugar levels in diabetics. As a precaution, however, you should discuss fish oil supplements with your health care provider, if you have diabetes. If you're already taking fish oil supplements, keep a close watch on how your blood sugar levels vary.
Another condition that can cause headache above left eye is glaucoma. This condition is due to the build-up of pressure within the left eye that causes damage to the optic nerve, destroying peripheral vision and leading to blindness. Any infections or tumor in the left eye or brain can cause pain around the eye.
More causes can also contribute to headaches developing behind the eyes, and they may be accompanied by several different symptoms. Headaches can frequently develop behind the left eye or both of the eyes. These headaches typically include shooting pains that start behind the eye and move throughout the head. Sometimes these are referred to as cluster headaches because they occur in clusters or cycles throughout the day.