Fifth Vital Sign? CGM for Glucose in Hospitals, Courtesy of COVID

Miriam E. Tucker

September 17, 2020

The emergency allowance of continuous glucose monitoring (CGM) devices in hospitals during the COVID-19 pandemic by the US Food and Drug Administration (FDA) appears to have facilitated a paradigm shift in the management of inpatient blood glucose.

Early in the pandemic, the FDA allowed use of two at-home CGMs — the Dexcom G6 and Abbott FreeStyle Libre 14-day system — in hospitals, despite neither being officially approved for inpatient use.

The move came amid growing concerns about the need to conserve personal protective equipment (PPE) supplies by minimizing the need for nurses to enter patients' rooms to perform fingerstick blood glucose checks, as CGM data can be transmitted wirelessly.

At the same time, increasing evidence pointed to diabetes and hyperglycemia as major risk factors for COVID-19 mortality.   

Just as outpatient "tele-diabetes" had been investigated and promoted by some groups prior to COVID-19, but was suddenly widely embraced out of necessity during the lockdown, a similar, albeit slower, phenomenon is occurring with CGM use in a growing number of US hospitals. 

In-Hospital CGM Use Propelled to the Forefront During Pandemic

Two research teams that had been in the process of conducting randomized clinical trials of inpatient CGM recently published interim data sooner than planned because of COVID-19.

One group, led by Elias K. Spanakis, MD, of the University of Maryland, Baltimore, was forced to halt their study due to the pandemic, but in their interim analysis of 72 general ward patients, use of real-time CGM (Dexcom G6) reduced hypoglycemia compared with point-of-care blood glucose testing alone. Those data were published online August 5 in Diabetes Care.

And at Scripps Whittier Diabetes Institute, San Diego, California, a team led by Athena Philis-Tsimikas, MD, reported interim findings on 110 of a total 404 patients in nonintensive care hospital settings randomized to either Dexcom G6 with wireless data transmission to the nurses' station or standard point-of-care glucose testing. The CGM group demonstrated significantly less hyperglycemia and greater percentage time in range. Those data were published online August 27 in Diabetes Care.

"Continuously streaming glucose readings may truly be the fifth vital sign," Philis-Tsimikas and coauthors conclude.

Diabetes technology expert David Ahn, MD, told Medscape Medical News: "As much as people talk about telemedicine being a huge win of COVID-19 — and obviously it is — I think another big development is the improvement of glycemic management in the inpatient setting. It's been a relatively ignored aspect of the inpatient world."

The sudden availability of CGM for inpatient use resulting from the pandemic "just shines a light on how behind inpatient management of diabetes is compared to all these fantastic tools we have in the outpatient setting," said Ahn, program director of the Allen Diabetes Center, Hoag Health, Newport Beach, California.

"Patients and doctors knew about it, but the barrier was safety and regulation," he added.

Ahn was a participant in a virtual 2-day Diabetes Technology Society (DTS) meeting on COVID-19 held August 26-27, 2020.

As part of the conference, several clinicians, including Spanakis, discussed their experiences with inpatient glucose management during the pandemic, as well as some of the fairly substantial barriers that must still be overcome before CGM use becomes standard of care for inpatients.

Inpatient CGM Use Saves PPE and Time

About 200 US hospitals and hospital systems have expressed interest in using the Dexcom G6 device, although not all have implemented it as yet, Dexcom president and CEO Kevin Sayer told Medscape Medical News.

The company is selling the sensors, transmitters, and dedicated mobile handsets to hospitals at a deep discount, and has developed new written training manuals and conducted virtual training for hospital staff. Dexcom has also just announced a new registry for tracking outcomes of in-hospital real-time CGM use in response to the pandemic.

While FDA did not place any restrictions on which inpatients can use CGM, most hospitals are using them in COVID-19 patients with hyperglycemia, whether or not they have a diabetes diagnosis.

Use has been primarily in larger centers on the East Coast and a few in the Midwest, with less uptake on the West Coast, according to Sayer.

For its part, Abbott donated 25,000 FreeStyle Libre 14-day sensors to the American Diabetes Association to distribute to US hospitals in outbreak hotspots.

Those devices aren't typically used in ICU settings because patients must be able to scan the transmitter themselves. (Medtronic, which also manufactures a stand-alone CGM, isn't participating.)

"I think CGM is a promising technology and the COVID-19 pandemic has accelerated the opportunity for doctors to test it out on patients," DTS conference Chair David C. Klonoff, MD, told Medscape Medical News in an interview.

According to Klonoff, who founded and directs DTS and is also medical director of the Dorothy L. and James E. Frank Diabetes Research Institute of Mills-Peninsula Medical Center, San Mateo, California, the current use of CGM in ICU settings during the pandemic is important for several reasons.

Patients who are on intravenous insulin drips typically need hourly blood glucose checks, which entail donning and doffing PPE each time. "Having CGM can free [the staff] up so they only have to check every few hours...and use the CGM data in between. So there's less exposure to the patients and better safety for the nurses. It also saves time."

Joshua D. Miller, MD, medical director of diabetes care at Stony Brook Medicine, New York, described his center's experience using 30 Dexcom G6 systems purchased soon after the FDA rule change, when New York was slammed with COVID-19 cases. At his facility, the devices were used in patients positive for COVID-19 with diabetes or severe hyperglycemia, admitted to ICU, and on insulin infusions. Most were also on ventilators.

They used a "hybrid" model, by which hourly point-of-care fingerstick testing continued for the first 24 hours after sensor insertion to ensure accuracy. If the correlation was within 20% of an arterial line-driven glucose value, then the nurses used the CGM data alternately with fingersticks throughout the patient's stay.

Importantly, the Stony Brook diabetes team was available 24/7 to address nurses' concerns. Keys to success, Miller said, are having a dedicated inpatient team, widespread institutional support with funding, help with training from industry, partnership with intensivists, and a "foundation of a diabetes culture," which at his institution includes a "glucometrics" dashboard initiated in 2014.

In an interview with Medscape Medical News, Miller said that the overall mortality rate for patients with COVID-19 at Stony Brook was far lower than for other institutions in the area, although CGM use was just one of many potential contributing factors.

Retrospective data on their first 30 patients with COVID-19 who used CGM will be published soon.

Challenges: Training, Ensuring Accuracy, and Institutional Buy-in

Of course, there remain many challenges before CGM use in hospitals can be fully established, and even for using it on a limited emergency basis during the pandemic.

Robert Rushakoff, MD, medical director for inpatient diabetes and professor of medicine at the University of California, San Francisco, has not implemented inpatient CGM during the pandemic, in a region that saw far fewer COVID-19 patients than did the East Coast in March and April.  

As he explained during the DTS meeting and in a subsequent interview with Medscape Medical News, Rushakoff believes that an emergency pandemic is not the time to introduce new technology into an already complicated situation.

"My take is that institutions should be doing what they do well. If they have protocols in place to manage blood sugars, they will work in COVID-19 patients. It's just that the insulin doses may be higher. We've had great blood glucose control in our patients just doing what we do, but dosing may be different. We don't use IV insulin in COVID-19 patients."

Rather, Rushakoff said, at his hospital the nurses "cluster" care, meaning that they accomplish as much as possible each time they enter the patient's room.

"The nurses are in the room every 4 hours anyway. We'll move the timing around so that patients are getting meals, blood glucose checks, insulin doses, and other meds all clustered together."

Barriers to broader inpatient CGM use, he said, include the need for extensive training of nurses in how to respond to the CGM data with protocols in place and standardized methods for entering the data into the electronic health record (EHR).

"This shouldn't be for 15 different groups to figure out...CGMs are absolutely the future, but this isn't the time to say that since we've used it in a handful of COVID-19 patients now we can use it in everyone. It doesn't go that way."

More Data, and Probably Hospital-Specific CGMs, Will Be Needed

Klonoff agrees that going forward "a lot has to happen. There are different levels of barriers."

Although the Dexcom G6 has eliminated many of the medication interference issues with prior versions — such as with acetaminophen (paracetamol) — there are still potential physiologic interferences, such as fluid changes, that could affect CGM function.

"Ultimately for FDA clearance there will need to be studies to show it's safe and effective in critically ill patients."

And the EHR challenge will take work. Currently, the only way is to download a PDF from an app such as Clarity — but that's not searchable — or manually enter the numbers.

"Each hospital is going to have to work with the companies so that the data flow directly into the EHR," Klonoff commented.

Ultimately, the experts agree that companies will need to develop inpatient versions of their devices and obtain FDA clearance for those, just as happened with fingerstick glucose meters.

That is on Dexcom's agenda, Sayer said.

"Over time we hope to develop a configuration to use in the hospital. We're excited about our ability to gather data [now] and see how our system performs in the hospital. The stories we've heard back are that it performs very well…but I think a hospital version is warranted."

Ideally, one difference from the home-use version would be a faster warmup time than the current 2 hours, during which readings are not available. "A faster warmup [will be] very important in the hospital," Sayer agrees.   

CGM Will Be a Powerful Tool in Hospitalized Patients

Looking past the pandemic, the experts see inpatient CGM as a future way not only to improve inpatient glycemic control but potentially to improve patient outcomes and safety, prevent readmissions, and ultimately save costs.

On the wards, Klonoff said, CGM can be particularly useful in helping to prevent hypoglycemia in patients on subcutaneous insulin in situations such as when they aren't eating, when they're being tapered off corticosteroids (increasingly used to treat COVID-19), or when they're weaned off non-oral nutrition.

"For all those reasons, blood glucose can drop lower than you expect...If the patient has an accurate CGM, it would send out an alarm. The nurse could then check with a fingerstick. This would be a warning and the nurse could save the patient's life...I would say avoiding what could be disastrous hypoglycemia is the most important use."

According to Miller, inpatient CGM could have a major impact for patients undergoing procedures unrelated to diabetes, such as in neurology or orthopedics, where medications that affect glucose levels are commonly used.

"Usually endocrinology gets consulted after the glucose levels have already skyrocketed…You can educate people, but it's not always top of mind…But gosh, if you had a CGM in place to help drive that message home I think it would fundamentally change our beliefs about blood sugar in the hospital."

"Not the tight glycemic control debates that we've been having for decades, but really just what happens to blood sugar in a hospitalized patient."

Sayer said another idea that's been discussed at Dexcom regarding a hospital-configured CGM is sending patients home with the sensor, thereby potentially reducing readmission rates. "Hospitals are looking at ways of monitoring high-risk patients after discharge."  

Ahn noted: "People say managing diabetes is just adjusting pills and you don't really get to see anything. But CGM really changes that. It's very rewarding. You don't have to have education to look at a CGM tracing and make changes to make it look good and feel better about it."

"That's why CGM is such a powerful tool for patients. I think it will be the same for nurses, where they have a better appreciation for it and take it a lot more seriously when they can see what's happening in response to the small things that they're doing."

Indeed, Miller commented, "Decades ago, when point-of-care glucose meters first became available, there was a steep learning curve. I think there will be a culture change but I will continue to say that CGM to patients with diabetes is as cardiac telemetry is to patients with coronary disease. It's just hands down."

Spanakis has reported receiving unrestricted research support from Dexcom (to Baltimore VA Medical Center and the University of Maryland). Ahn has reported being a consultant with Senseonics and Lilly, and on the speaker's bureau for Lilly. Miller has reported being a consultant for Medtronic Diabetes and Ascensia Diabetes. Klonoff has reported being a consultant for Dexcom, Eoflow, Fractyl, Lifecare, Novo, Roche, Thirdwayv, and Samsung. Sayer is a Dexcom employee. Rushakoff has reported no relevant financial relationships.

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