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Clinical Topics

Continuous Glucose Monitoring Highly Effective But Underused in Diabetes

by Brenda Mooney

June 19, 2018

EAST ORANGE, NJ — Recent clinical studies have documented why continuous glucose monitors (CGM) can offer significant benefits to patients diagnosed with diabetes. The devices not only improve overall blood glucose control, they also reduce the risk of dangerous hypoglycemia, researchers have found.

Yet, use of CGM is not as widespread as some experts expected it to be. In fact, at the end of last year, when diabetes experts from around the world came together to develop guidelines on the use of continuous glucose monitoring in diabetes patients, they discussed the issue.

Their recommendations, printed in the journal Diabetes Care, were straightforward: “CGM should be considered in conjunction with HbA1c for glycemic status assessment and therapy adjustment in all patients with Type 1 diabetes and patients with Type 2 diabetes treated with intensive insulin therapy who are not achieving glucose targets, especially if the patient is experiencing problematic hypoglycemia.”1

The authors pointed out, however, “Despite a growing body of evidence of the clinical benefits of CGM and the continually improving accuracy of CGM devices, this technology is not yet widely used. The nationwide T1D Exchange clinic registry, which includes 76 endocrinology practices and >26,000 enrolled subjects with Type 1 diabetes, recently reported 11% CGM use overall, compared to 62% use of insulin pump therapy across all age groups. In addition, documented CGM use tends to decrease over time, although less so in adult patients.”

Leonard Pogach, MD, MBA — VA Medical Center, East Orange, NJ

“Literature suggests patient-level factors such as alarm fatigue and perceptions of inaccuracy or interference with daily life are barriers to CGM usage and adversely impact patient acceptance,” explained Leonard Pogach, MD, MBA, of the VA’s Office of Specialty Care Services and the VA Medical Center-East Orange in New Jersey. “Advances in technology may lead to increased acceptance of CGM technology.”

At the VA, 124 veterans have been issued CGM devices over the past three years, Pogach noted. According to VA policy, any VA endocrinologist can request CGM and/or insulin pumps for insulin-dependent patients. Documentation of Type 1 diabetes is not required, and no age restrictions are in place, he added.

To obtain a continuous glucose monitor, the requesting endocrinologist states a clinical need, such as improved control, management of hypoglycemia or any other considerations, Pogach explained, pointing out that the ability of the patient to use the device must be determined. Then, a second level review is required from a lead endocrinologist at the VISN level.

“Although the CGM request must originate from a VA endocrinologist, the patient-issued CGM can be managed by a diabetes team, either within the VA or the private sector,” he noted. “Veterans issued CGM need to be reevaluated at least annually for compliance and continued use of the CGM device.”

While some guidelines recommend use of the technology in Type 2 diabetes patients, the primary focus thus far has been on patients with Type 1 diabetes. A recent six-month clinical trial compared the use of CGM for adult patients with Type 1 diabetes to daily use of test strips. Researchers determined that the costs were within the range usually covered by insurance plans.2

The study published in Diabetes Care, also calculated the costs and health effects over the expected lifetime of patients, finding that CGMs actually increased quality of life by extending the amount of time patients enjoy relatively good health, free of complications.

“If you map out the lifetime of a patient, it’s impressive. The CGM adds years of life and years of quality life,” said senior author Elbert Huang, MD, Associate Director of the Chicago Center for Diabetes Translation Research at the University of Chicago. “While it does cost additional money, the costs saved by lower risk of complications offsets the upfront costs.”

For the randomized trial, researches focused on 158 patients with Type 1 diabetes who relied on multiple, daily injections of insulin but not an insulin pump. Two-thirds of the group used CGMs, and the remaining third used the finger prick method with test strips and a meter to check their blood sugars.

The longer-term simulation calculated quality-adjusted life years (QALYs) for each patient, with CGM projected to reduce the risk of complications from Type 1 diabetes and increase QALYs by .54, which translates into an additional six months of good health.

Advances in CGM technology will also continue to lower costs, as it further integrates with software and everyday digital devices such as smartphones.

“It hints at a future of chronic disease management that’s more cost effective and gives patients more control,” Huang 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.”

The issue in expanded use at the VA at this point isn’t cost but demographics. The prevalence of Type 1 diabetes in the United States is about 5%, and the vast majority of patients develop it prior to age 20. Because a diabetes diagnosis prevents military enlistment, the percentage of veterans with Type 1 diabetes is estimated to be lower than the general population.

On the other hand, about a fourth of veterans treated by the VA have Type 2 diabetes, which has an older patient population. Some, but not all, of those patients with Type 2 diabetes might be candidates for CGM, Pogach suggested, adding, “Many have significant co-morbid conditions other than diabetes that can impact glycemic control goals and the use of CGM technology.”

“Limited evidence suggests that it may be of benefit in T2DM patients treated with basal-bolus insulin,” he said.

As more trials show benefit for CGM in type 2 diabetes, additional guidance on broader use —such as by the international consensus group —is likely to be issued. How closely those will be followed remain an open question, however.

Those authors cited “multiple reasons why this technology is not embraced in clinical use to the same degree as other technologies such as insulin pump therapy. Some obstacles identified include cost and reimbursement issues, clinicians’ unwillingness to learn or implement new technology, and user factors such as alarm fatigue and perceptions of inaccuracy or interference with daily life.”

Barriers to Use

Among the barriers are the discomfort of needle sticks and the constant need to recalibrate. In approving the first CGM not requiring blood sample calibration —or needle sticks —the Food and Drug Administration addressed some of those issues.

“The FDA is always interested in new technologies that can help make the care of people living with chronic conditions, such as diabetes, easier and more manageable,” said Donald St. Pierre, acting director of the Office of In Vitro Diagnostics and Radiological Health and deputy director of new product evaluation in the FDA’s Center for Devices and Radiological Health. “This system allows people with diabetes to avoid the additional step of fingerstick calibration, which can sometimes be painful, but still provides necessary information for treating their diabetes—with a wave of the mobile reader.”

He was discussing the FreeStyle Libre Flash Glucose Monitoring System, “the first continuous glucose monitoring system that can be used by adult patients to make diabetes treatment decisions without calibration using a blood sample from the fingertips,” according to the FDA. The system uses a small sensor wire inserted below the skin’s surface that continuously measures and monitors glucose levels.

With the potential to overcome some of the barriers to CGM update, the VA sees the device as another tool to meet one of its primary goal: sharing decision-making with patients.

The VA’s diabetes treatment guidelines developed last year with DoD strongly bolstered the move toward personalized treatment, using a formal process of shared decision making. Having continuous information potentially could empower patients.3

While VA does not track clinical outcomes of patients receiving CGM, Pogach pointed out, “the VA/DoD Diabetes Clinical Practice Guidelines, always emphasized setting individualized target glycemic control goals based upon the individual patient’s circumstances and preferences and clinician/patient shared decision-making.”


1Danne T, Nimri R, Battelino T, Bergenstal RM, et. Al. International Consensus on Use of Continuous Glucose Monitoring. Diabetes Care. 2017 Dec;40(12):1631-1640. oi: 10.2337/dc17-1600. Review. PubMed PMID: 29162583.

2Wan W, Skandari MR, Minc A, Nathan AG, 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. Diabetes Care. 2018 Apr 12. pii: dc171821. doi: 10.2337/dc17-1821. [Epu ahead of print] PubMed PMID: 29650803.

3Conlin PR, Colburn J, Aron D, Pries RM, Tschanz MP, Pogach L. Synopsis of the 2017 U.S. Department of Veterans Affairs/U.S. Department of Defense Clinical Practice Guideline: Management of Type 2 Diabetes Mellitus. Ann Intern Med. 2017 Nov 7;167(9):655-663. doi: 10.7326/M17-1362. Epub 2017 Oct 24. PubMed PMID:29059687.

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