There are two ways that vision becomes blurry due to diabetes. The first way occurs around the time of diagnosis and is related to poorly controlled blood sugar. The second way that vision is decreased from diabetes is from diabetic retinopathy; the eye disease caused by diabetes. The actual eye disease usually develops years after the diagnosis of diabetes is made.
Usually, patients diagnosed with diabetes have elevated blood sugar due to insufficient supplies of insulin. Insulin, produced by the pancreas, is a hormone that takes sugar out of the bloodstream and allows it to be used as fuel for our cells.
Not enough insulin ... blood sugar levels skyrocket.
With large elevations of sugar, vision can be affected. The large amount of sugar can enter part of the eye, and eventually, the sugar permeates the natural lens of the eye.
The sugar, glucose, is altered slightly inside the lens to sorbitol, a derivative of the glucose. Both sugar and sorbitol attract water. As a result, the increased water content of the lens, changes the focusing power of the eye causing a change in the vision.
In other words, high sugar concentrations lead to increased water content of the eye. This changes the vision and also the strength of the glasses needed to see well.
There is usually a lag between sugar control and stable vision. The vision may stabilize after a few weeks of controlled sugar.
Once the blood glucose has become controlled with medication and has been stable for a few weeks, it is then time to visit the eye doctor.
The eye doctor, ophthalmologist or optometrist, should be checking you for glasses, and for the presence of diabetic retinopathy.