People of African-Caribbean ethnicity with Type 2 diabetes are a third more likely to develop a condition called sight-threatening diabetic retinopathy (STDR) than other ethnic groups, according to researchers from King's.
The study, published in the journal Diabetes Care, examined risk factors for STDR in a large, ethnically diverse group of more than 8,500 people with type 2 diabetes across South London. It found that individuals of African-Caribbean ethnicity were 35% more likely to develop STDR, even when adjusting for other risk factors, such as age, high blood glucose, high cholesterol and deprivation.
Diabetic eye disease is the leading cause of sight loss in working age adults in the UK and many countries worldwide. Our results highlight the need for further research on the role of ethnicity and associated mechanisms that may explain enhanced risk of diabetic retinopathy progression."
Janaka Karalliedde, Clinical Professor of Diabetes, King's and Consultant Physician in Diabetes and Endocrinology and Internal Medicine, Guy's and St Thomas Hospital London
More than 4 million people in the UK have type 2 diabetes, with the disease disproportionally affecting non-white communities. It is the leading cause of blindness in the UK in working age adults. Diabetic retinopathy is a term used to describe the damage diabetes causes to the small blood vessels in the retina - the light-sensitive layer at the back of the eye. Between 20 and 30% of people with diabetes have retinopathy, and nearly 2,000 people lose sight due to diabetic eye disease each year in the UK.
STDR, a subset of diabetic retinopathy, is the name used when the condition has progressed to a stage where an individual is at risk of losing their vision. Although often symptomless at the beginning, damage from long-term blood sugar can cause changes to occur quickly and cause irreversible vision loss if untreated.
In the study, which was led by Professor Janaka Karalliedde, Clinical Professor of Diabetes, King's, and funded by Guy's and St Thomas' Charity, the researchers recruited adults with type 2 diabetes and no diabetic retinopathy. They then studied clinical, biochemical and socio-economic data from these individuals by collecting their results from the UK National Diabetic Eye Screening Programme, which tests people with type 2 diabetes annually. Data was collected between 2004 and 2018, and participants were followed over an average of 8.9 years each.
Over the course of the study, 489 people - nearly 6% - developed STDR. The researchers used statistical analysis techniques to separate the individual risk factors, revealing that African-Caribbean ethnicity led to a 35% higher likelihood of developing STDR alone. This effect was independent of well-known risk factors such as longer diabetes duration, high cholesterol, high blood sugar levels and socio-economic deprivation.
This important study highlights a reality many of us in eye care have long suspected which is that people of African-Caribbean heritage living with type 2 diabetes face a higher risk of sight threatening retinopathy, even after accounting for blood sugar, cholesterol and deprivation. In ophthalmology, we see similar disparities in glaucoma, where Black people tend to develop disease earlier and present later with more advanced vision loss. And beyond eyes, the same patterns are mirrored in breast cancer, prostate cancer and maternal mortality."
- Dr Evelyn Mensah, Consultant Eye Surgeon, President Ophthalmology Section of the Royal Society of Medicine, London North West University Healthcare NHS Trust
Dr Mensah continued: "The relevance of systemic factors should be considered in future research. With diabetes eye screening intervals increased to every two years for low-risk groups, we must be careful not to apply a blanket approach that risks widening health inequities. Screening programmes and hospital eye services must respond to the needs of diverse communities if we are to ensure excellent visual outcomes for all."
The researchers call for more work to understand why African-Caribbean ethnicity is linked to greater STDR risk, including possible genetic, biological and social mechanisms. They also suggest healthcare providers consider ethnicity as a potential risk factor when assessing and monitoring eye disease in people with diabetes.
