High blood sugar may impact the blood vessels of the light sensitive tissue behind the retina. This is called diabetic retinopathy.
Floaters: One may be able to see spots or dark strings floating in the vision.
Fluctuating vision: Elevated blood may cause blurry vision affecting the sight and fluctuating vision.
Eye pain: This is an early warning sign. High blood sugar levels may put pressure and cause unexplained pain in the eyes.
Blurred vision: When glucose levels increase, it may put pressure in the area that helps the eye focus causing blurry eyesight.
Vision Loss: In case of seriously high diabetes, the swelling can damage the eye muscles detaching retina from back of the eye causing sudden vision loss.
This is generic information and no substitute to medical advice. If you suspect any of these signs, immediately contact a doctor.