✅ Medically reviewed by Dr Sharon Heng
How Does Diabetes Affect the Eye?
The global prevalence of diabetes is 9.3% in 2019 (estimated 463 million) and this is expected to rise to 10.9% by 2045. The prevalence of diabetes is found to be higher in high income and urban nations as compared to rural and lower income countries.
Diabetes can affect the eyes in many ways, including cataracts and diabetic retinopathy and diabetic macular oedema. So what exactly is diabetic retinopathy and diabetic macular oedema? The retina itself is the light-sensitive layer of cells located at the back of the eye.
This layer converts light into electrical signals which are then sent to the brain and turns them to the images we see. The retina is supported by a network of small blood vessels to supply it with its nutrition and remove waste materials. The high sugar levels in diabetes can damage these tiny blood vessels over a period of time.
The phase of damage range from mild background retinopathy (small bleed in the eye and will not cause visual problems) to pre proliferative (more wide spread bleed in the eye, usually picked up during eye screening or examination and will not cause visual problems) and visual compromising proliferative retinopathy – where new vessels are noted and bleeding or possible retina detachment occurs which can impact on vision.
The retina needs a constant supply of blood, which it receives through a network of tiny blood vessels. Diabetic Macular Oedema (DMO) itself is accumulation of fluid in the macular, which is the center of the eye where the highest concentration of nerve cells sits. This fluid may compromise vision if it affects the fovea or may cause distortion.
Implications of Comorbidities Control on Diabetic Eye Disease
When your doctor uses the term co-morbidities, they usually refer to the other medical conditions that coexist with diabetes. Examples are high blood pressure or hypertension and hypercholesterolemia. There are risk factors which makes a patient more susceptible to diabetic retinopathy and these include:
Patients with type I or II diabetes
The risks increases if one has had diabetes for a long time
Poorly controlled sugar levels
Have hypertension or high blood pressure
Have high cholesterol
Pregnant
Are of Asian or Afro-Caribbean background
Have had diabetes for a long time
Systemic control of diabetes, hypertension, and hypercholesterolemia in earlier studies in 1980s-1990s have been shown to have positive effects on reduction of progression of diabetic retinopathy and vision loss. It is key to optimise the control of your blood sugar, blood pressure and cholesterol levels.
Latest Research Results from New Diabetic Treatment and Their Impact on the Eyes
There has been several advancement in the treatment of diabetes (not within the scope of this article) including new treatment such as sodium-glucose cotransporter 2 (SGLT-2) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists in type II diabetic patients, insulin pumps, diabetic home monitors etc.
Newer treatment such as SGLT2 inhibitors have been approved to be used for type 2 diabetic patients who require further optimization of their glucose levels despite metformin therapy. These treatments have also shown to have a positive impact on atherosclerotic cardiovascular disease and chronic kidney disease.
So What is the Impact of SGLT-2 Inhibitors on the Eyes?
Preclinical studies also showed early evidence of the protective role of SGLT2 inhibitors such as Dapagliflozin for both diabetic nephropathy (kidney disease) and diabetic retinopathy. SGLT2 inhibitor lowers blood glucose levels, reduces body weight and reduces blood pressure by inhibiting glucose absorption in the proximal tubule which is a part in the kidneys and promotes urine glucose excretion or removal.
Recently, real world analysis of patients across Asia (Taiwan) and America has shown that SGLT2is has consistently decreased the risk of sight threatening retinopathy and diabetic macular oedema in patients with type II diabetes. The impact is noted across different subgroups of patients, including age and gender.
What if I Already Have Diabetic Retinopathy and Diabetic Macular Oedema?
If one already has the more advanced stages of diabetic retinopathy such as proliferative diabetic retinopathy or sight compromising macular oedema, please see your eye doctor for a detailed consultation and possible treatment.
There are treatments available such as panretinal photocoagulation and intravitreal anti-VEGF therapy or injectable steroid implant which has shown to have very good results to stabilise or improve vision depending on the stage or prognosis of the disease.
In summary
Prevention is always better than cure where possible. It is advisable to optimise the control of glucose, hypertension, and hypercholesterolemia to prevent diabetic retinopathy and other retina vascular diseases.
Newer treatments for diabetes such as SGLT2 inhibitors have also shown positive impact on reducing the risk of various diabetic complications including diabetic retinopathy and diabetic macular oedema.
Ms Heng has keen interest in personalised therapy that individualises a patient's treatment in accordance to their other health needs, work needs, and personal needs. Keep yourself updated with the latest developments in eye care – continue to follow our blog and speak to us today!
References
Sodium-Glucose Cotransporter 2 Inhibitors and Risk of Retinopathy in Patients With Type 2 Diabetes. Yen et al JAMA Netw Open. 2023;6(12):e2348431. doi:10.1001/jamanetworkopen
Risk of diabetic retinopathy and diabetic macular oedema with sodium–glucose cotransporter 2 inhibitors and glucagon-like peptide 1 receptor agonists in type 2 diabetes: a real-world data study from a global federated database. Eleftheriadou et al Diabetologia 67, 1271–1282 (2024).
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