People with advanced stages of retinopathy, even when glucose is very high, need to be very careful while controlling their blood sugar as a sudden reduction after prolonged uncontrolled diabetes can worsen the retinopathy, says Dr Jyothydev Kesavdev, research diabetologist based in Kerala, in an interview with Anna Jose. Edited excerpts:
Diabetes is emerging as a major cause of blindness globally. How serious is the problem?
As the prevalence of diabetes is increasing, the prevalence of blindness is also increasing. Currently, it is said there are three million people who are at immediate risk of vision loss due to diabetic retinopathy. Currently, diabetic retinopathy is the sixth cause of blindness in India; earlier it was the 17th cause of blindness, but because of uncontrolled diabetes, it has now gone up. In diabetes, there are three illnesses that can affect the eye: retinopathy, glaucoma, and cataracts. Cataracts affect the eye when we are aging, but in uncontrolled diabetes, cataracts set in very early, and hence, they are also regarded as a disease related to uncontrolled glucose. When we say that there are more than 110 million people with diabetes in India, one in five people with diabetes in the country have signs of diabetic retinopathy.
How does diabetes affect the retina and lead to vision loss?
When there is a consistent increase in glucose levels or when there are fluctuations in the level of glucose, we call it glucose variability. It results in advanced glycation, oxidative stress, and endothelial damage. The small blood vessels in the retina get affected, and there will be blot and dot haemorrhages and lipid deposits, resulting in changes in the retina that can be visualised through fundoscopy or a retinal camera. These help detect very early changes in the retina, including retinopathy, early glaucoma, or age-related macular degeneration. Vision can be retained if it is in the early stages of retinopathy.
When should people with diabetes undergo retinal screening?
When somebody is diagnosed with type-2 diabetes, immediately you should be checking the retina. Even though it takes many years for diabetes to affect the eye, diabetes itself is often diagnosed after many years because it can remain asymptomatic for six to eight years. By that time, retinopathy could have already set in. Even during the diagnosis of diabetes itself, more than 10% of people will have manifestations of retinopathy. In type-1 diabetes, which affects children and rarely adults and older people, the recommendation is to examine the retina five years after diagnosis. If somebody with diabetes is planning to get pregnant, you have to check the retina before planning for pregnancy and during the first trimester, because retinopathy can worsen during pregnancy.
What role does blood sugar control play, and can rapid reduction in glucose worsen retinopathy?
When somebody is having retinopathy or macular edema, a sudden reduction in glucose levels after prolonged uncontrolled diabetes can worsen the retinopathy. Medicines like insulin or the once-weekly GLP-1 injections are very powerful and potent. Patients with diabetic retinopathy also need to be careful with medicines such as pioglitazone, which can worsen macular edema.
Does diabetic retinopathy occur in isolation?
Retinopathy doesn’t occur alone. It is part of microvascular complications. If somebody’s retina is affected, it is quite normal and quite usual to have the nerves and also the kidneys affected. Along with routine diabetes consultation, we recommend a foot check-up, ECG, body composition analysis, and laboratory investigations to check the status of the liver, kidney, thyroid, lipids, heart, and CRP levels. The doctor, along with the nurse, educators, and dietitian, will help the patient keep glucose within the target range and personalise the diet because different foods affect different people differently.