A long-term study in England has found that older adults with poorly controlled diabetes are much more likely to develop eye disease, including diabetic retinopathy, glaucoma and macular degeneration, compared to those with healthier blood sugar levels.
Published July 9 in BMJ Open, the study followed more than 5,600 adults aged 52 and older for 14 years. Researchers found that participants with high blood sugar at the start of the study had a 31% chance of developing diabetic eye disease. Those with lower levels had just a 9% chance.
People with undiagnosed diabetes, meaning elevated blood sugar but no formal diagnosis, also faced higher risk. They were 38% more likely to develop macular degeneration and 23% more likely to develop diabetic eye disease compared to individuals whose diabetes was well managed.
Diabetic eye disease most often refers to diabetic retinopathy, a condition where high blood sugar damages blood vessels in the retina, the light-sensitive tissue at the back of the eye. People with diabetes also face increased risk for glaucoma (damage to the optic nerve) and macular degeneration, which affects the center of the retina and can lead to vision loss.
“These findings show how important it is that people with diabetes are diagnosed and are supported in managing the condition, as this will reduce their chance of potentially debilitating eye disease,” said Dr. Stephen Jivraj, co-author and researcher at the UCL Institute of Epidemiology & Health Care.
The research drew from the English Longitudinal Study of Ageing, a national study that surveys participants every two years. People were grouped by diabetes status: no diabetes, controlled diabetes, uncontrolled diabetes (a blood test showing average blood sugar levels above 6.5%, which is the threshold for diabetes) or undiagnosed diabetes.
By the end of the study period, those with uncontrolled diabetes had more than triple the odds of developing diabetic eye disease compared to those managing their condition.
“The study highlights the importance of eye examinations among those in older age, especially those with a diabetes diagnosis,” said first author Caitlin Lin, now a PhD candidate at the UCL Global Business School for Health. “It also supports wider testing for diabetes in the general population, to reduce the number of people who do not realise they have the condition and could therefore be at a higher risk of eye disease.”
The study did not find a significant difference in cataract risk between groups. The authors noted that the number of participants responding to surveys declined over time, which may have affected final estimates.
The authors reported no specific funding for this research.