Trial Finds Glucose Monitors Help Diabetes Patients Who Don't Use Insulin, Reopening Insurance Debate

A large federally registered clinical trial has found that continuous glucose monitors, long reserved by insurers mainly for people with diabetes who inject insulin, produced significant blood-sugar improvements in adults with type 2 diabetes who do not use insulin at all. The findings, published this past week in The New England Journal of Medicine, are already reshaping arguments over who should get the devices covered by insurance.

The trial, called CONNECT, randomly assigned 283 adults with type 2 diabetes who were not on insulin to either wear a continuous glucose monitor, or CGM, for 26 weeks or to continue routine fingerstick self-testing. The results were announced in a University of Colorado Anschutz Medical Campus announcement on October 14, the same day the peer-reviewed paper appeared in the journal.

The numbers

Participants, who had a mean age of 60 and a median diabetes duration of ten years, were enrolled at 22 primary care practices around the country and continued their usual medications, including metformin, GLP-1 receptor agonists and SGLT2 inhibitors, throughout the study. Those wearing Dexcom's G7 sensor saw their average A1C, a measure of blood sugar control over roughly three months, fall from 8.8 percent to 7.2 percent. The control group's A1C dropped from 8.7 percent to 8.0 percent. The 0.9-percentage-point difference between the groups was statistically significant and, researchers said, well above the threshold generally considered clinically meaningful.

Eighty-two percent of CGM users achieved an A1C reduction of at least half a percentage point, compared with 56 percent of those in routine care. CGM users also spent roughly five more hours a day with blood sugar in the healthy range of 70 to 180 milligrams per deciliter, an improvement that researchers said began within the first week of wearing the sensor and held steady through the end of the trial. No serious adverse events were reported in either group, and 97 percent of participants were still using their monitor at the 26-week mark.

How CGM use for diabetes evolved

Continuous glucose monitors, small sensors worn on the skin that track blood sugar in real time and send readings to a phone or receiver, have been standard practice for more than a decade for many people with type 1 diabetes and for people with type 2 diabetes who inject insulin. Insurance coverage, including Medicare's, has largely followed that line: people on insulin generally qualify, while people with type 2 diabetes managed through pills, lifestyle changes or non-insulin injectables such as GLP-1 drugs typically have not.

That split was built into clinical guidance. Under the American Diabetes Association's 2026 Standards of Care, CGM use for people on insulin or at risk of low blood sugar carries the association's strongest evidence grades, while the recommendation for people with type 2 diabetes who are not on insulin had rested on weaker, observational evidence. CONNECT is the study researchers say was designed specifically to close that gap: according to the trial's registration with the federal clinical trials database, it is the first large, multicenter, randomized controlled trial built to test CGM's effectiveness and safety in exactly this population, delivered through ordinary primary care offices rather than specialty diabetes clinics.

Who is affected

The population in question is large. The Centers for Disease Control and Prevention estimates that about 38 million Americans have diabetes, with type 2 accounting for roughly 90 to 95 percent of diagnosed cases. Tamara Oser, the study's first author and a professor of family medicine at the University of Colorado Anschutz, put the number of U.S. adults with type 2 diabetes who are not on insulin at about 20 million, a group she said has so far lacked the kind of rigorous trial evidence that drove coverage decisions for insulin users.

Medicare currently does not broadly cover CGM for people in that group, and most private insurers have followed Medicare's lead. That has left millions of patients paying out of pocket, often several hundred dollars a month, if they want to use the technology before starting insulin.

"CGM substantially improved glycemia in adults with type 2 diabetes not using insulin," said Thomas W. Martens, medical director of the International Diabetes Center in Minneapolis, who presented the trial's results. "Notably, the combination of GLP-1 and CGM had the highest treatment difference differential."

Reaction

Roy Beck of the Jaeb Center for Health Research in Tampa, the trial's senior author, said the consistency of the benefit across different patients and treatment regimens "supports consideration of the use of a CGM much earlier in Type 2 diabetes management before insulin is needed." Diana Isaacs, an endocrine clinical pharmacist at the Cleveland Clinic who was not involved in running the trial, wrote in commentary on the findings, reported by the medical news outlet Healio, that the results represent a major practice implication and that she hopes they influence payer coverage decisions.

Several of the clinicians who discussed the trial publicly, including Martens and Isaacs, disclosed financial relationships with Dexcom and competing device makers such as Abbott and Medtronic, as is common in diabetes technology research. The study itself was funded by Dexcom, whose G7 sensor was the device tested; the company's chief executive, Jake Leach, called the publication "a significant moment for the CGM category" and urged insurers to expand access. Trade coverage of the trial, including a report from the industry publication MedTech Dive, noted that financial analysts see the publication as a likely catalyst for a decision by the Centers for Medicare & Medicaid Services on whether to widen coverage.

What happens next

CMS has not announced a coverage decision, and the agency's review timeline remains unclear. Analysts who cover Dexcom and Abbott have told investors they expect a decision on expanding Medicare's CGM coverage policy within the next several months, with device makers estimating that a change could extend eligibility to millions of additional Medicare beneficiaries with type 2 diabetes. Those projections are industry estimates, not confirmed agency plans.

Separately, researchers are continuing to follow CONNECT participants through a six-month extension phase to see whether the glucose improvements seen at 26 weeks persist at one year, data that could further inform both clinical guidelines and insurance decisions. For now, the study's authors say their immediate recommendation is more modest: that adults with type 2 diabetes who are not on insulin raise the option of continuous glucose monitoring with their primary care provider, rather than assuming the technology is only for people who inject insulin.

"It's important we continue to improve care for everyone with diabetes," Oser said in the university's announcement of the findings.