A new study from University College London’s Institute of Epidemiology and Health Care, London, UK, has highlighted a compelling link between blood sugar control and the long-term risk of developing several major eye diseases in those aged over 50.
Using data taken from the English Longitudinal Study of Ageing (ELSA) – a panel study aimed at capturing “a holistic view on the ageing experience of those residing in private households in England” – the study looked at over 5,600 adults aged 52 and older over a period of 14 years. The researchers examined how blood sugar status — including diagnosed, undiagnosed, controlled, and uncontrolled diabetes — influenced the onset of glaucoma, diabetic eye disease, macular degeneration, and cataract.
Participants’ HbA1c levels and self-reported diagnoses were analyzed, alongside lifestyle factors such as smoking, body mass index (BMI), and physical activity level.
The findings indicate that patients with well-controlled diabetes were consistently less likely to develop glaucoma, diabetic eye disease, and macular degeneration than those with uncontrolled or undiagnosed diabetes. In fact, even individuals without diabetes and whose blood sugar levels did not exceed the clinical diabetic threshold had a higher probability of developing glaucoma than those effectively managing their blood sugar — a result that surprised the authors and warrants further investigation.
Uncontrolled diabetes significantly increased the likelihood of developing diabetic eye disease and macular degeneration over time. Meanwhile, the probability of developing cataracts rose steadily in all groups regardless of diabetes status, reinforcing its strong association with aging itself rather than glycaemic control.
The study supports the idea that proactive diabetes management may offer protective effects beyond just retinopathy prevention, as well as strengthening the argument for earlier and more frequent eye screenings in older adults. In order to achieve this, the authors advocate for broader public health strategies, including earlier diabetes screening and greater access to eye exams before turning 60 (the current eligibility age for free National Health Service ((NHS)) eye tests in the UK).
