Diabetes leads to higher-than-average glucose levels in your blood, which increases the pressure on the insides of your blood vessels, contributing to high blood pressure. Pressure also increases in the small blood vessels in your eyes.
Over time, the excess pressure causes the blood vessels to leak fluid into your eye. This causes swelling in your macula, also known as macular edema. Your macula is a small part of your retina that performs a critical function: It’s the part of your eye that allows you to see what’s right in front of you.
When left untreated, diabetic retinopathy can lead to blindness.