A gradual change in eyesight may be an early sign of diabetes, according to Mr Chien Wong, a consultant ophthalmic surgeon and director at OCL Vision. Statistics from Diabetes UK reveal that almost six million people in the UK live with diabetes. While around 4.7 million have received a confirmed diagnosis, approximately 1.3 million remain unaware they have the condition.
Undiagnosed and untreated diabetes can lead to serious health complications such as blindness, heart disease, kidney and nerve damage, and even amputations. Eye problems are not often the first symptoms noticed, but blurred vision can sometimes be an early and easily overlooked indicator.
This blurring occurs because the lens inside the eye may swell when blood sugar levels rise too high or fall too low, causing temporary but noticeable vision distortion that can affect one or both eyes. Over time, persistently high blood sugar can damage the retina, the light-sensitive layer at the back of the eye, by causing tiny blood vessels to leak fluid and leading to swelling.
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In some cases, damaged vessels stop functioning, resulting in the growth of fragile new blood vessels which may bleed. If untreated, this can progress to more severe conditions like retinal detachment or glaucoma.
Mr Wong notes that nearly everyone with type 1 diabetes and around two-thirds of those with type 2 diabetes will develop some form of diabetic eye disease within 20 years of diagnosis. He emphasises the importance of regular eye checks, explaining that the retina offers a direct insight into overall body health.
“Detecting damage at an early stage gives a real chance to protect sight,” he said. “Once noticeable vision changes occur, some damage may be irreversible.”
He also highlights that a sudden appearance of floaters-small dots or specks drifting across the field of vision-can indicate bleeding inside the eye and requires urgent specialist attention. Vision changes usually do not occur alone; the NHS lists other warning signs of diabetes, including increased thirst, frequent urination (especially at night), persistent tiredness, unexplained weight loss, and recurring thrush.
Mr Wong urges anyone experiencing gradual or sudden vision changes not to dismiss these as normal ageing, but to seek medical advice promptly. Regular eye examinations remain a simple yet effective way to detect diabetic eye disease before it jeopardises vision.