People with Type 1 diabetes are generally more likely to develop diabetic retinopathy than Type 2 patients. In fact, virtually all people who have had Type 1 diabetes for 15 years or more have some degree of diabetic retinopathy. Among people with Type 2 diabetes, duration of disease is also an important risk factor. Insulin-taking Type 2 patients who have had diabetes for five to 10 years have about a 2 percent incidence of proliferative retinopathy. This rate increases to more than 50 percent in insulin-taking Type 2 patients who have had diabetes for more than 20 years.
Diabetic retinopathy is a complex disease.
Although scientists understand much about the disease s natural history, they are still unclear about its specific pathological causes. There is, however, a consensus that diabetic retinopathy probably does not stem from a single retinal change. Rather, the disease may be triggered by a combination of biochemical, metabolic, and hematologic abnormalities. A chronic increase in normal blood-glucose levels may gradually alter cell metabolism in the retinal blood vessels. Blood platelet abnormalities.