A man named Chai went blind after 17 years as a diabetic.
Five years ago, his second daughter began having blackouts in her vision. These blackouts would sometimes last for 2-3 months. When the blackouts completely blocked her vision, she went for a checkup and found that they were induced by diabetes. At the same time, his first daughter who had blurry vision since middle school, also began to have blackouts.
Apparently, dilation of the blood vessels to the retina alleviated their blackouts and poor eyesight.