The Role for CGM in Glycemic Management Will Continue to Expand, Including in Prediabetes, Expert Says

"There’s real potential for [continuous glucose monitoring] to be part of a proactive approach to glycemic management early in the course of disease, maybe even before a formal diabetes diagnosis," Thomas Martens, MD, told Patient Care during an interview at the 2025 ACP Internal Medicine Meeting this month.

After his presentation Beyond A1C: Using Continuous Glucose Monitoring to Improve Type 2 Diabetes Management in Primary Care, Patient Care asked him to talk more about how he sees the role of CGM evolving in diabetes care, including whether there is a role for the new over-the-counter (OTC) models.

The video transcript has been lightly edited for style.

Patient Care: A version of the CGM is now available over-the-counter for anyone to use. How do you see the landscape of monitoring evolving over the next 3 to 5 years and how might an OCT CGM fit in?

Thomas Martens, MD: That’s a great question—and the landscape is definitely changing.

At this point, it's pretty clear that continuous glucose monitoring (CGM) is a win for people managing diabetes with insulin. For patients with type 1 diabetes, CGM should be considered standard of care. And for those with type 2 diabetes who use insulin, there’s solid evidence showing they benefit from CGM access. Coverage is improving in both of these groups.

The open question remains for a large segment of the type 2 population: those not using insulin. The data in this area is growing. While we don’t yet have randomized controlled trial (RCT) data, there’s a lot of observational evidence suggesting CGM could be helpful here, too. But without strong RCTs, coverage for non-insulin users remains limited. As a result, many people in this group still don’t have meaningful access to CGM.

That’s where over-the-counter CGM devices may come in. They offer a potential path to access at a semi-reasonable price—though of course, “reasonable” varies by individual. Still, when compared with the cost of newer diabetes medications like GLP-1 receptor agonists or SGLT2 inhibitors—which are excellent but expensive—CGM starts to look relatively affordable.

These devices could allow people to use CGM intermittently to better understand the impact of diet and other lifestyle factors. I think that’s a real opportunity. And I expect that the RCTs currently underway will provide supportive data within the next few years. So in the next 3–5 years, I believe we’ll continue to see this space evolve. My sense is that CGM will become increasingly useful across the board—even in prediabetes.

There’s real potential for CGM to be part of a proactive approach to glycemic management early in the course of disease, maybe even before a formal diabetes diagnosis. If you think about the UKPDS (United Kingdom Prospective Diabetes Study), conducted almost 30 years ago, they looked at people with newly diagnosed type 2 diabetes. Participants were randomized to a target HbA1c of 7.9% versus below 7%, and followed for 10 years. Those in the lower A1c group—what they called "aggressively managed"—had better cardiovascular and microvascular outcomes.

What’s really compelling is that those patients continued to show benefits over time. At the 10-year mark, and even at the 24-year follow-up published last year, the group that received earlier, tighter glucose control had better mortality outcomes and fewer complications. It suggests that the early years of type 2 diabetes are critical in setting the course for long-term outcomes.

So as we think about tools like CGM, the value may go beyond glucose tracking. It can provide real-time feedback that helps people recognize the impact of specific food choices. When people can see what’s happening, they can respond—and that’s powerful.

Ultimately, I believe CGM will play an increasing role in helping patients make informed decisions early in the disease process, with the goal of avoiding complications down the road.