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.
Pain Behind Your Eye. Common causes of pain behind the eyes are migraine headaches and sinus infections. In the case of a migraine headache, the pain almost always is behind only one eye and often is accompanied by pain elsewhere on the same side of the head.