Your concerns are definitely right and it is a serious development in you which should be examined as early as possible.
Diabetes can damage the small blood vessels in your retina, the back part of your eye,resulting into the condition called as diabetic retinopathy
Symptoms of diabetic retinopathy include shadows or missing areas of vision,floaters,blurred vision
There can be other problems in diabetics namely cataracts
Consult a eye doctor urgently.