High blood sugar over time can also damage the small blood vessels in the retina, causing diabetic retinopathy. Without appropriate treatment, this condition may lead to serious vision problems.
Difficulty concentrating and feeling mentally exhausted can also occur when blood glucose levels are significantly elevated or fluctuate substantially. However, these symptoms have many possible causes and should not automatically be attributed to diabetes.
Anyone experiencing sudden vision loss or a sudden change in eyesight should seek urgent medical attention.