"Diabetic retinopathy — vision-threatening damage to the retina of the eye caused by diabetes — is the leading cause of blindness among working-age Americans. The good news: Diabetic retinopathy often can be prevented with early detection, proper management of your diabetes and routine eye exams performed by your optometrist or ophthalmologist. According to the International Diabetes Federation (IDF), the United States has the highest rate of diabetes among 38 developed nations, with approximately 30 million Americans — roughly 11 percent of the U.S. population between the ages of 20 and 79 — having the disease.
About 90 percent of Americans with diabetes have type 2 diabetes, which develops when the the body fails to produce enough insulin — a hormone secreted by the pancreas that enables dietary sugar to enter the cells of the body — or the body becomes resistant to insulin. This causes glucose (sugar) levels in the bloodstream to rise and can eventually damage the eyes, kidneys, nerves or heart, according to the American Diabetes Association (ADA).
Risk factors for type 2 diabetes include obesity, an unhealthful diet and physical inactivity. Unfortunately, the prevalence of obesity and type 2 diabetes has increased significantly in the United States over the past 30 years."
Source - All About Vision