Continuous Glucose Monitoring Lowers Risk of Diabetic Retinopathy

The use of continuous glucose monitoring by patients with type 1 diabetes was associated with lower odds of developing diabetic retinopathy, according to a study recently published in the JAMA Network Open.

Diabetic retinopathy affects the blood vessels in the retina and can cause vision loss and blindness. The condition can develop in both patients who have type 1 diabetes or type diabetes.

The use of continuous glucose monitoring — devices to automatically estimate blood glucose levels to provide real-time updates throughout the day — has risen. One study, published in January 2024, found that 49.8% people with type 1 diabetes in the sample of those with commercial insurance used the devices from 2016 to 2019, up from 20.1% from 2010 to 2013.

Patients with type 1 diabetes are more at risk for diabetic retinopathy than those with type 2 diabetes. In a study published last year, 30% of the patients with type 1 diabetes had diabetic retinopathy.

Risa M. Wolf, M.D.

Researchers from the JAMA Network Open paper suggested that insulin therapy, coupled with reduced HbA1c levels (which measure blood glucose), could the risk and progression of diabetic retinopathy. Risa M. Wolf, M.D., director, Pediatrics Diabetes Program, associate professor of Pediatrics at Johns Hopkins University School of Medicine, and her colleagues, wanted to assess whether the use of continuous glucose monitoring could help patients with type 1 diabetes lower their risk of developing diabetic retinopathy.

They conducted a retrospective cohort study in patients with type 1 diabetes. They analyzed electronic medical records from both Johns Hopkins Endocrine and Diabetes Center and the Wilmer Eye Institute in Baltimore from 2013 to 2021.

Wolf and her colleagues first assessed the use of continuous glucose monitoring technology of those with diabetic retinopathy. These were patients who had visits in both the diabetes center and the ophthalmology clinic. A second analysis assessed the progression diabetic retinopathy.

Of the 624 adults with type 1 diabetes who had visits to both the diabetes center and the ophthalmology clinic, 550 were using continuous glucose monitoring at the beginning of the study period. Of these patients, 44.4% had a diagnosis of diabetic retinopathy.

Researchers found that use of continuous glucose monitoring was associated with lower the risk of developing diabetic retinopathy, as well as lowering the risk of the disease progressing. They suggested that the use of such technology reduces variability in glucose levels.

“Compared with users who self-monitored their glucose with fingerstick blood glucose monitoring (BGM), CGM users had more time spent within the glycemic target range and lower A1C levels,” they wrote. “CGM users, compared with nonusers, also had a significantly lower risk of hypoglycemia-related admission to an emergency room or hospital and a reduced risk of all-cause hospitalization.”

One limitation that researchers identified was that they did not assess people with Medicare or Medicaid coverage and this could be an area for future examination.

Costs and lack of coverage for continuous glucose monitoring could be one reason for the slow uptake of these devices. The majority of patients in this study had their devices covered as durable medical equipment, but researchers point out that in the more recent time frame of the study, more patients used their prescription coverage to access CGM. Insurance issues could become a barrier, they said, for ensuring access.

“Widespread use of CGM could help people achieve better glycemic control and reduce complications associated with type 1 diabetes,” researchers concluded.