If you ask us, it’s about darn time someone organized a study demonstrating that it’s safe to make insulin dosing decisions based on continuous glucose monitoring (CGM) data, without the need to do a backup fingerstick test each time.
The ability to rely on CGM data is of course key to creating a closed loop system, but to date, no one has taken on the specific task of quantifying the accuracy for dosing decisions… until now.
Supported by the T1D ExChange network, the study is being run by their research partner, the Jaeb Center for Health Research in Tampa, FL, and taking place at 15 different hospitals around the country – with 15 patients each in the trials, for a total of 225 patients participating. The lead researchers are Dr. Roy Beck and Katrina Ruedy, who recognize what a landmark this work represents.
“Many individuals with T1D who are using CGM technology often rely solely on the CGM device when bolusing insulin, despite its labeling as an ‘adjunctive tool’ for management. If insulin dosing decisions are proven to be safe and effective using CGM without BGM confirmation, this study could help pave the way for a new standard for using CGM that would minimize the number of fingerstick measurements a day and ease the burden of managing type 1 diabetes,” Ruedy tells us.
As you can read on ClinicalTrials.gov, the participants are all over 25 years old, have had type 1 diabetes for between one and 40 years, and have used an insulin pump for at least 3 months.
For the study, they’re being randomly assigned to the CGM Only or CGM + Fingerstick Meter groups. In advance of this, researchers collected about 10 weeks of “blinded baseline CGM data” to get a sense of standard CGM use.
The study is using the Dexcom G4 Platinum CGM with the most up-to-date algorithm, and the new Universal Device Uploader being developed by Tidepool, which is now in beta format, to view and access data from the CGM as well as various BG meters and insulin pumps (!)
“They needed a data management provider for this study, and they found Tidepool. The Uploader they’re testing is the same version that we’ll be releasing to the public at the end of June,” Arbiter tells us, adding that this opportunity really helps move Tidepool’s work forward.
“It’s been our vision that Tidepool is a platform, that others can develop apps on top of. Now Jaeb is the first app developer, as they’ve created an app specifically to use for this study.”
Each patient will use the system for three months, and these timeslots are “staggered,” so the study will go on for circa 6-9 months, Arbiter explains.
Note that despite the use of the G4 product, Dexcom as a company is not officially involved in this study. But as we've reported previously, the company is in hot pursuit of a “dosing claim” to file with FDA, i.e. an approval of the CGM as a replacement for fingerstick testing -- that would also eliminate the need for those pesky calibrations.
In November, Dexcom's executive VP of strategy and corporate development Steve Pacelli told us: "The FDA is very keen on us running a trial and the Artificial Pancreas needs a (CGM) sensor that is dosing-worthy. We were going to wait for a future generation to add in this advanced algorithm, but the FDA was ready for that now."
And in our interview with Dexcom CEO Kevin Sayer last week, he said:
“It's a huge issue. Every endo we talk to asks us: When will you get Medicare coverage (for CGM)? We are pursuing a legislative path with others (such as Medtronic, AACE, and JDRF) and will continue on that path. But we're spending a lot of time discussing the dosing claim, as Medicare has told us they won't cover CGM as a supplementary device. You have so much more information to dose with a CGM, and we wonder why this is even such a discussion. But it's important to getting that dosing designation and we're talking with the FDA about the structure for clinical trials. The legislation was introduced last year but died in Congress, and we expect it to be reintroduced soon.”
While the dosing claim is being studied as an independent issue by both the REPLACE-BG trial and by Dexcom itself, CGM competitor Medtronic (makers of the only other CGM system on the market) are weaving that into product development studies of their new hybrid closed loop system, that will automatically determine how much insulin to deliver based on CGM values. This system builds on their next-gen MiniMed 640G paired with a future sensor, and the company is currently "engaging with FDA" to kick off the next round of clinical trials in the next few months, spokeswoman Karrie Hawbaker tells us.
We're sure glad to hear about the REPLACE-BG study moving forward now to assure there will finally be clinical evidence to support CGM as a reliable tool on its own!
Sorry, fingerstick meter manufacturers. This may be bad news for you, but we patients using CGM are impatient for it.
*** UPDATE February 2017 ***
The FDA approved the dosing claim for Dexcom G5 in December 2016, making it the first and only CGM considered to be "as good as fingersticks" and sanctioned for use in treatment decisions. Final Replace BG Study data was published on Feb. 15, 2017, supplying additional clinical evidence that the Dexcom CGM is safe enough to use for insulin dosing decisions.