Diabetes primarily affects the blood vessels that nourish the retina. The retinal vessels work like a garden hose, bringing oxygen and other nutrients into and out of the eye. Diabetes can also make the blood vessels close off. These new vessels do not help the eye, however. They are fragile and can cause blindness by hemorrhaging or retinal detachment.
Diabetic retinopathy develops gradually over many years.
Type I diabetes, those requiring insulin to control their blood sugar, and patients with diabetes for many years are at an increased risk for developing retinal problems. Poor control of the blood glucose, pregnancy, uncontrolled high blood pressure, and smoking also aggravate diabetic retinopathy. You can't diagnose diabetic retinopathy by looking in the mirror since your eye will usually look and feel normal. Vision is also often normal despite the presence of potentially blinding eye conditions. Only a thorough retinal examination through a dilated pupil can detect these problems.