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Study Suggests Cost-Effectiveness of CGM Will Rise as Technology Improves


Researchers found that cost-effectiveness calculations shifted dramatically when they assumed people with diabetes used continuous glucose monitoring (CGM) sensors for 10 days instead of 7 days. This is significant because Dexcom just received approval for a next-generation CGM system with a factory-calibrated 10-day sensor.

On their own, results published last week in Diabetes Care were welcome news among advocates for covering continuous glucose monitoring (CGM) systems: A study from the University of Chicago found that CGM use falls within accepted cost-effectiveness thresholds used by health plans to cover medical devices.

What’s more, the researchers found that cost-effectiveness increased when their models mimicked what happens in the real world. A CGM system uses a device called a sensor inserted under the skin to test blood sugar every few minutes and feed the results to a receiver or, increasingly, to patients’ smartphones. The FDA approval for the device tested in the Diabetes Care study calls for the sensor to be replaced every 7 days.

But the researchers noted that in practice, patients seeking to save money wear sensors up to 10 days. This makes a difference in the cost-effectiveness calculations. And as sensors continue to last longer—given what’s in the pipeline—the cost-effectiveness argument will tilt even more heavily in favor of CGM, allowing the technology to penetrate beyond those with type 1 diabetes (T1D) to the 29 million Americans who have type 2 diabetes (T2D).

Study Results

New results from the DIAMOND study evaluated 158 patients with T1D who started the study with glycated hemoglobin (A1C) of at least 7.5% and were randomized 2:1 to use either CGM or test strips to monitor their blood glucose. Patients were measured at baseline and at 6 months. While those using CGM had higher overall costs at 6 months—$11,032 compared with $7236—much of this was the upfront cost of the CGM, at $2554. (Patients in the study used a Dexcom CGM.)

Patients using CGM had a significant difference in A1C reduction, 1.0% compared with .04%. Those using CGM also had fewer nonsevere episodes of hypoglycemia. Researchers found that over a lifetime, a person with T1D would have fewer major complications and would see an increased life expectancy of 0.72 years. When calculated as a cost per quality-adjusted life-year (QALY) gained, these differences translated into CGM had an incremental cost effectiveness ratio (ICER) of $98,108 per QALY, based on 7-day sensor use.

“If you map out the lifetime of a patient, it’s impressive,” Elbert Huang, MD, associate director of the Chicago Center for Diabetes, said in a statement. “The CGM adds years of life and years of quality life. While it does cost additional money, the costs saved by lower risk of complications offsets the upfront costs.”

Implications and the Pipeline

Based on 10-day sensor use, the University of Chicago researchers found the ICER decreases to $33,459. This is relevant since last month Dexcom received approval for the G6, a next-generation system with a factory-calibrated 10-day sensor; this device will be available in the second quarter of 2018. Dexcom is working on a 14-day sensor and hopes to gain approval in 2019.

Also last month, an FDA advisory panel approved a 90-day implantable sensor, the Eversense by Senseonics, which works with a removable transmitter worn over the sensor site.

Medicare’s decision in 2017 to approve Dexcom’s G5 CGM for those with T2D on intensive insulin therapy—defined as at least 4 injections per day—was seen as a breakthrough to gaining CGM coverage in commercial market for more patients with T2D. The discussion of just who in the T2D population should use CGM has been a hot topic in diabetes management circles—but one major point in CGM’s favor is that it causes no side effects and has been shown to be effective with some patients with A1C levels of 9% or higher.

As Jeremy Pettus, MD, of the University of California at San Diego, said last year during a discussion at the American Diabetes Association Scientific Sessions, when patients with uncontrolled glucose levels see the effects of food and exercise in real time, it can be “empowering.”

Huang uses similar language to describe the integration of CGM into diabetes care, as technology improves and costs come down. “It hints at a future of chronic disease management that’s more cost-effective and gives patients more control,” he said. “Basically, all the CGM does is provide information, but that allows patients to change the way they eat or time their medications. It empowers patients to manage their own health.”


Wan W, Skandari MR, Minc A, et al. Cost-effectiveness of continuous glucose monitoring for adults with type 1 diabetes compared with self-monitoring of blood glucose: the DIAMOND randomized trial [published online April 12, 2018]. Diabetes Care. doi: 10.2337/dc17-1821.

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