Diabetes can affect your eye in a number of ways:
The most serious eye condition associated with diabetes involves the network of blood vessels supplying the retina. This condition is called diabetic retinopathy.
The unusual changes in blood sugar levels resulting from diabetes can affect the lens inside the eye, especially when diabetes is uncontrolled. This can result in blurring of vision which comes and goes over the day, depending on your blood sugar levels.
A longer term effect of diabetes is that the lens of your eye can go cloudy, This is called a cataract.