PHILADELPHIA- Although the prevalence of diabetes-related eye diseases almost doubled since 2014, the rates of most severe forms of the disease have actually decreased, according to a new study led by researchers at the Perelman School of Medicine at the University of Pennsylvania. The researchers believe their findings, published in Ophthalmology, demonstrate the adeptness of health care providers in the United States in diagnosing and treating diabetes over the years. At the same time, they believe it could also provide a glimpse of potential vision-threatening diseases lying in wait in the future.
"Our work shows that more than 30 percent of all patients with diabetes now have some form of diabetic retinal disease, which means that the number of people at risk for vision loss continues to grow," said lead author Brian VanderBeek, MD, MPH, MSCE, an associate professor of Ophthalmology "But our work has maybe also revealed that the most severe forms of the disease are becoming less common, suggesting clinicians may be getting better at treating systemic diabetes."
Since more than 10 percent of the United States population, 38 million people, are now diagnosed with diabetes, and over 98 million have pre-diabetes-numbers that have been steadily growing for decades-it is vital to obtain a full picture of the risks associated with the disease, including development of diabetic retinal disease that could ultimately lead to vision loss so that health workers and public health officials can accurately assess and address them.
To gain a picture of how diabetes has been affecting patients' eyes, VanderBeek and his colleagues analyzed a database of deidentified medical claims from more than six million patients who already had or had been diagnosed with diabetes while enrolled in commercial insurance and Medicare Advantage plans between 2000 and 2022.
The researchers used two measurements: prevalence and incidence. Prevalence measures the percentage of the studied population that is diagnosed with each condition (both new diagnoses and old). Incidence is the rate that new cases of disease occur.
What the numbers showed
Analysis indicated that the proportion of people with diabetes who have any diabetes-related retinal diseases (conditions affecting the retina, the light-sensing tissue at the back of the eye) compared to those in the study population with just diabetes jumped from 10.8 to 20.8 percent between 2014 and 2021.
The incidence rate "varied considerably" according to the study authors, but, overall, it almost doubled from its lowest rate, 17.7 new cases per 1,000 person-years (a statistical measure used to represent new cases over time) in 2013 to 32.2 in 2022.
However, not all diabetic retinal diseases lead to blindness. Some forms of the disease are more "vision-threatening," meaning they can result in reduced vision or blindness, which the researchers also tracked in the data. The prevalence of these vision-threatening conditions varied, but each of the conditions that the researchers considered to be the most severe forms has decreased 10 percent over the last several years. Incidence rates showed more dramatic improvements. For all forms of the vision-threatening conditions, the incidence rate dropped 51 percent from 2009 to 2022 (12.4 cases per 1,000 person-years to 6.1 in 2022).
The incidence rate of one of the most severe forms of the disease, proliferative diabetic retinopathy, fell by almost 300 percent since 2002, going from 8.3 per 1,000 person-years to just 2.6 in 2022.
Behind the numbers
The seemingly contradictory changes in the rise of diabetes-related conditions affecting the eye but incidences of vision-damaging conditions going down could have two also diverging explanations, VanderBeek said.
One possible explanation is that more people are getting diabetes and diabetic retinal diseases, but the data hasn't caught up to these new patients, meaning that a future tsunami of vision-threatening diagnoses could be just over the horizon.
But VanderBeek said he believes a second explanation: that diabetes care as a whole is getting better, which has a positive effect on preventing the most severe forms of the disease.
"Oddly, one of the reasons for that, I think, is the same as why we have more diabetes retinal diseases being diagnosed: The population has become better insured over the years we studied because of things like the Affordable Care Act, which gave people access to care and screening," VanderBeek said.
Moving forward, the study team hopes to further analyze the data collected in the database to gain insight into some of the subpopulations within the study, uncovering what kind of changes occurred below the surface.
"That includes measuring disparities across race and ethnicity, as well as changes within the Type 1 and Type 2 diabetes populations," said VanderBeek.
This study was funded by the Research to Prevent Blindness/Mary Tyler Moore Vision Initiative Physician-Scientist Award and the National Eye Institute (1R21EY035707).
