One year after the U.S. Food and Drug Administration (FDA) approved the first over-the-counter (OTC) continuous glucose monitoring (CGM) devices, two experts will draw on the past several months of data and clinical experience to assess the impact of these devices.

Debate: Over-the-Counter Continuous Glucose Monitoring—Data for All or a Disaster Waiting to Happen? will take place on Friday, June 20, from 12:45–1:45 p.m., in Room W183 BC of the McCormick Place Convention Center, featuring Diana Isaacs, PharmD, BCPS, BCACP, BC-ADM, CDCES, advocating the “Data for All” position, and David Ahn, MD, making the case that the devices are a “Disaster Waiting to Happen.” On-demand access to recorded presentations will be available to registered participants following the conclusion of the 85^th Scientific Sessions, from June 25–August 25.

A Year of Non-Prescription Access

In March 2024, Dexcom’s Stelo became the first device to receive FDA approval for non-prescription CGM devices. Abbott’s Lingo gained FDA approval in June 2024.

The devices are marketed for people with prediabetes, people with type 2 diabetes who do not take insulin, and for people not living with diabetes. Each device resembles a prescription CGM counterpart in operating platforms, wearability, and functioning, but the non-prescription CGMs do not give alarms for hypoglycemic or hyperglycemic events and have a more limited reading range of real-time glucose levels.

Though no comprehensive data is available on the number of people around the world who regularly wear non-prescription CGMs, the potential user base is enormous. In the U.S. alone, there are nearly 98 million people with prediabetes.

Data for All

Dr. Isaacs, an endocrine clinical pharmacy specialist and Co-Director of Endocrine Disorders in Pregnancy at the Cleveland Clinic Endocrinology & Metabolism Institute, characterized the non-prescription CGMs—along with the accompanying informational videos and data access points—as being “an innovative way” to reach and educate people who might purchase the devices without having been diagnosed.

“There is so much undiagnosed type 2 diabetes and prediabetes. This type of accessible data will hopefully enable people to uncover many more cases,” Dr. Isaacs said. “We know that the longer a person waits, the worse their outcome. These devices provide a real potential to lower that risk.”

Dr. Isaacs said clinicians can anticipate how people will use and benefit from non-prescription CGMs because of the scenario that has played out with prescription CGMs.

“When prescription CGM use was growing, we had concerns about certain patients using it because they might be anxious about the data, but we have completely changed our tune because we have seen how beneficial using CGMs is. It is now standard of care for type 1 and for any insulin user,” Dr. Isaacs said.

Disaster Waiting to Happen

One of the key strengths of the non-prescription CGM devices is also their fundamental weakness, said Dr. Ahn, Chief of Diabetes Services at Hoag, a health care system in Orange County, California.

Non-prescription CGMs derive from highly accurate and highly calibrated prescription devices for people with type 1 diabetes, or who have type 2 diabetes and take insulin. These devices have now been modified for a different population but remain fundamentally purposed for their original audience. In effect, while the device can generate an immense amount of data, it might not be entirely clear what that data means for people with prediabetes or without diabetes. 

Dr. Ahn noted one example of misapplying previous CGM concepts is that clinicians can’t clearly define an unhealthy glucose spike versus a healthy glucose spike for people with prediabetes or without diabetes, which he said is “potentially very worrisome.”

These concerns are repeated with other key phenomena, such as pressure lows and accepted margins of error for glucose readings.

“In our enthusiasm to expand CGM and who uses it, it is important that we are not blind to its shortcomings,” Dr. Ahn said.

Living in a Continuous World

While Drs. Ahn and Isaacs will present the strongest cases for their respective positions, they said they also want the debate to raise important conversations about non-prescription CGMs, as well as broader trends of wearable medical technology and the role of metabolic health in chronic disease management.

In clinical terms, knowing more about the devices improves care.

“I think it is important to be familiar with them, because people are going to be using them and we need to know how to access and interpret the data from them,” Dr. Isaacs said.

And, in terms of research opportunities, both Drs. Isaacs and Ahn pointed to the possibility that studying data from non-prescription CGMs could illuminate relatively blank areas of knowledge about standard time in range (TIR) and standard range levels for people with prediabetes and others—insights that could benefit people with and without diabetes.

“Right now, we don’t have a lot of data on people without diabetes,” Dr. Ahn said. “What should someone’s glycemic tracing be? How do you define metabolic health? We don’t know. We have a few papers, but there is no clear consensus.”