The simple answer is yes. An estimated 750,000 people in the UK have diabetes but don't know it, according to Diabetes UK. If untreated, the life-threatening condition can lead to impaired vision or even blindness. An eye test can reveal the signs of diabetes. Over time a high blood-glucose level can weaken and damage the tiny blood vessels next to the retina. Your local Vision Express Optician may be able to spot what's known as a 'dot haemorrhage' or tiny leak from a damaged blood vessel, which is one of the indications of diabetes. If you think you may be diabetic it is also important to have regular general health checks as an eye test alone may not be sufficient in diagnosing this condition.