An international panel of experts called for users of continuous glucose monitoring (CGM) to stay within the recommended target range 70% of the time, according to evidence-based guidelines presented Saturday during the 79th Scientific Sessions of the American Diabetes Association (ADA).
For most users, keeping blood glucose levels between 70 mg/dL and 180 mg/dL for 16.8 hours per day would ensure that person’s glycated hemoglobin (A1C) level stays below 7%, the panel reported in a manuscript, “Clinical Targets for Continuous Glucose Monitoring Data Interpretation: Recommendations from the International Consensus on Time-in-Range.” The paper appeared in Diabetes Care
, while its findings were unveiled during ADA in San Francisco, California.
CGM technology has made leaps in recent years, with more accurate sensors and, in some models, factory calibration that free users from needle sticks multiple times a day. While more patients are using CGM—it is considered standard of care for type 1 diabetes (T1D)—the panel concluded that “successful utilization of CGM technology in routine clinical practice remains low.”
Indeed, data presented
by the T1D Diabetes Exchange show that A1C levels for this group are rising, even though CGM use has climbed from 7% to 30% between 2010-2012 and 2016-2018. Although A1C levels are generally lower among CGM users, they are worse for other groups, including teenagers. Authors of the Diabetes Care
article say that although peer-reviewed articles have established key metrics for CGM use, formal adoption of guidelines by diabetes professional organizations did not follow—until now.
In recent years, both clinical researchers and advocacy groups have pressed for time in range to gain recognition as a key measure in diabetes care, one that should have consideration alongside A1C as a marker of glycemic control and overall health.
The paper’s lead author, Tadej Battelino, MD, head of the department of pediatric and adolescent endocrinology at Ljubljana University Medical Centre in Slovenia, described the use of time-in-range as a complement to A1C. But others see time-in-range as so important that it may someday replace A1C as the best indicator of future complications.
Leading diabetes researcher and clinician Anne Peters, MD
, professor of medicine at the Keck School of Medicine at the University of Southern California, went so far as to say that "probably the A1C is a useless number” during a meeting of The Institute for Value-Based Medicine®
presented by The American Journal of Managed Care®
Development of time-in-range guidelines took shape in February 2019 when the Advanced Technologies & Treatments for Diabetes (ATTD) Congress convened an international panel that included physicians, researchers, and people living with diabetes. Subgroups formed to review literature and make evidence-based recommendations for each population, which were presented to the full panel and put to a vote. Modifications to the general recommendations were made for older and high-risk users, and those using CGM during pregnancy.
Battelino briefed members of the media on the group’s consensus recommendations, and encouraged wide dissemination “to improve outcomes and reduce the burden of diabetes.” Guidelines are as follows:
Type 1/Type 2 Users
Older/High-Risk Users, Both Type 1 and Type 2
- The target of 70 mg/dL to 180 mg/dL should be maintained at least 70% of the time.
- CGM users should allow low blood glucose levels of at least 70 mg/dL for less than 4% of the day, or about 1 hour, and very low levels of less than 54 mg/dL for no more than 1% of the day, or 15 minutes.
- Users should allow blood glucose of more than 180 mg/dL for less than 25% of the time, and very high levels of more than 250 mg/dL for less than 5% of the time.
Pregnant Users With T1D
- The target of 70 mg/dL to 180 mg/dL should be maintained more than 50% of the time.
- Avoiding hypoglycemia is a priority in this population, so CGM users should allow low blood glucose levels of less than 70 mg/dL for less than 1% of the day, or 15 minutes.
- Users should allow blood glucose of more than 180 mg/dL for less than 50% of the time, and very high levels of more than 250 mg/dL for less than 10% of the time.
Pregnant Users With Type 2 Diabetes (T2D) or Gestational Diabetes
- A target of 63 mg/dL to 140 mg/dL should be maintained more than 70% of the time.
- Pregnant CGM users with T1D should allow low blood glucose levels of less than 63 mg/dL for less than 4% of the day (1 hour) and very low levels of less than 54 mg/dL for less than 1% of the day (15 minutes).
- Users can keep blood glucose of more than 140 mg/dL to less than 25% of the time, or 6 hours.
- A target of 63 mg/dL to 140 mg/dL should be maintained.
- Because of the lack of evidence on CGM targets for women with gestational diabetes or T2D in pregnancy, percentages of time spent in range, below range and above range were not provided.
How can the guidelines be implemented into clinical practice? The consensus group called for translating the new CGM targets in a standard report, such an ambulatory glucose profile, or AGP Report.
“These standardized CGM metrics and targets will be instrumental in improving care for people with diabetes,” Battelino said in a statement
. “In a clinical practice setting, time in ranges are both appropriate and instrumental outcome measurements that, like A1C levels, are an integral component of treatment decisions.”
Besides the ADA, groups endorsing the report are the American Association of Clinical Endocrinologists, American Association of Diabetes Educators, European Association for the Study of Diabetes, Foundation of European Nurses in Diabetes, International Society for Pediatric and Adolescent Diabetes, JDRF, and Pediatric Endocrine Society.
Battelino T, Danne T, Bergenstal RM, et al. Clinical targets for continuous glucose monitoring data interpretation: recommendations from the international consensus on time-in-range [published online June 8, 2019]. Diabetes Care
. 2019; doi.org/10.2337/dci19-0028.