6. Glaucoma

People with diabetes are twice as likely to develop glaucoma, or the increased pressure of fluids found inside the eye. Neovascular glaucoma, a rare type of glaucoma, is a result of the damage in retinal blood vessels caused by diabetes. This damage to the retina forces it to manufacture new, abnormal blood vessels which can reach the iris (the colored part of the eye), blocking fluid flow within the eye thus increasing pressure inside.