Retinopathy can occur with all types of diabetes. If left untreated, diabetic retinopathy can lead to blindness.

The classic symptoms include 'fidgety', 'crawling' or 'jittery' feelings in the lower limbs usually occurring in bed at night, but occasionally developing after periods of prolonged sitting when the person affected is physically and mentally tired.

The sensations are experienced mostly in the calves and although usually present in both legs, one side can be affected more severely than the other. Relief is generally obtained by movements such as walking. In some cases the sufferer has to spend much of the night pacing up and down to achieve any lasting improvement.

Some people even notice spasmodic jerking movement of their legs during their sleep, which can occasionally disturb their partners too.

In mild cases there is only a moderate degree of discomfort but in more severe cases considerable discomfort, distress and sleep interruption is experienced.

There is an increased risk of retinopathy:

with poor blood sugar control, ie levels are too high for too much of the time
if there's protein in your urine
if you have high blood pressure
the longer you've had diabetes
if you have raised levels of fats (triglycerides) in the blood
the more swellings you have (microaneurysms)
with pregnancy (but not in diabetes caused by pregnancy)..

This list has some things in common with that for diabetic kidney disease.