A new consensus report provides "time in range" targets for people with diabetes who use continuous glucose monitoring (CGM).
The recommendations were also presented June 9 at the American Diabetes Association (ADA) 2019 Scientific Sessions and published online June 8 in Diabetes Care.
In a late-breaking poster, Tadej Battelino, MD, PhD, head of the department of pediatric and adolescent endocrinology at Ljubljana University Medical Centre, Slovenia, detailed the document entitled, Clinical Targets for Continuous Glucose Monitoring Data Interpretation: Recommendations From the International Consensus on Time in Range.
The report was developed by a panel convened by the Advanced Technologies & Treatments for Diabetes (ATTD) Congress.
The recommendations are endorsed by the ADA, American Association of Clinical Endocrinologists (AACE), American Association of Diabetes Educators (AADE), European Association for the Study of Diabetes (EASD), Foundation of European Nurses in Diabetes, International Society for Pediatric and Adolescent Diabetes, JDRF, and Pediatric Endocrine Society.
Time in range targets are provided for most people with type 1 and type 2 diabetes, for those who are older or at high risk for severe hypoglycemia, and for pregnant women. Recommendations are given for upper and lower blood glucose targets and for time spent in both target and out-of-target ranges.
"CGM use continues to expand in many countries...However, glycemic control remains suboptimal and successful use of CGM in clinical practices remains low. This may be due in part to the lack of clear and agreed-upon targets for this new way of monitoring and making decisions in diabetes," Battelino said during a press briefing at ADA.
The targets aren't meant to replace but to complement HbA1c measurement, he said in response to a question from Medscape Medical News.
"The evidence behind HbA1c is immense, so that stays. Time in range is more a day-to-day target...It's supplementing HbA1c and meant to be used mainly by people with diabetes."
Asked to comment, Steven Russell, MD, of Massachusetts General Hospital, Boston, told Medscape Medical News, "I am not necessarily a believer that time in range is the best metric."
"Personally, I think we're better off using mean glucose and time in hypoglycemia as the two criteria. Mean glucose is more closely correlated to HbA1c, and HbA1c is what we have this long-time connection to regarding risk of complications."
Time in Range Recommendations
In the document, the recommendations for most people with type 1 or type 2 diabetes are:
- > 70% of readings within a blood glucose range of 70-180mg/dL (3.9-10.0 mmol/L)
- < 4% of readings < 70 mg/dL (< 3.9 mmol/L)
- < 1% of readings < 54 mg/dL (< 3.0 mmol/L)
- < 25% of readings > 180 mg/dL (> 10.0 mmol/L)
- < 5% of readings > 250 mg/dL (> 13.9 mmol/L)
- For those aged < 25 years for whom the HbA1c goal is < 7.5%, the time-in-range target should be set toabout 60%.
For older adults or those at high risk for hypoglycemia (ie, have hypoglycemic unawareness, cognitive impairment, or comorbidities):
- > 50% of readings within 70-180 mg/dL (3.9-10.0 mmol/L)
- < 1% of readings < 70 mg/dL (< 3.9 mmol/L)
- < 10% of readings > 250 mg/dL (> 13.9 mmol/L)
For those with type 1 diabetes who are pregnant:
- > 70% of readings within 63-140 mg/dL (3.5-7.8 mmol/L)
- < 4% of readings < 63 mg/dL (< 3.5 mmol/L)
- < 1% of readings < 54 mg/dL (< 3.0 mmol/L)
- < 25% of readings > 140 mg/dL (>7.8 mmol/L)
Each incremental increase of 5% time in range is associated with clinically significant benefits for people with type 1 and type 2 diabetes, including among women who are pregnant and have type 1 diabetes, the document notes.
Goals are also given in terms of actual amount of time per day.
For pregnancy in type 2 diabetes or gestational diabetes, the target range is also 63-140 mg/dL (3.5-7.8 mmol/L) but no further guidelines are provided because of insufficient evidence.
"We conclude that, in clinical practice, time in ranges (within target range, below range, above range) are both appropriate and useful as clinical targets and outcome measurements that complement HbA1c for a wide range of people with diabetes and that the target values specified in this article should be considered an integral component of CGM data analysis and day-to-day treatment decision-making," Battelino and colleagues conclude.
Is Mean Glucose a Better Metric?
Most CGM device download software already reports 14-day "time in range" data as ambulatory glucose profile (AGP) reports and could be modified to incorporate the new targets, Battelino noted at ADA.
But those reports also include mean glucose values, which Russell believes are more helpful when combined with time spent with glucose < 54 mg/dL.
"Although mean glucose and time in range do correlate, I think mean glucose provides more important information because you could have two people with identical time in range but different means...There isn't as much of a body of evidence linking time in range to complications."
However, Russell does agree with Battelino regarding the importance of CGM use for people with diabetes taking multiple daily doses of insulin.
"I think CGM should be standard of care in type 1 diabetes," he stressed.
And "in type 2, people on multiple daily injections have the same challenges in managing glucose. For those people, I also think CGM should be standard of care, absolutely."
Battelino said: "The proposed CGM time in range targets and standardized presentation with AGP may facilitate the routine use of CGM and improve clinical outcomes of diabetes management…but, they will only be workable if individuals with diabetes endorse them in their daily lives."