For many patients with diabetes who use continuous glucose monitoring, the percentage of each day spent within, above, and below target range can be a useful complement to HbA1c levels in clinical decision making, according to a new consensus report.
Adoption of the technology has grown rapidly over the past few years as a result of improved sensor accuracy, greater convenience and ease of use, and expanding reimbursement, the report noted. However, while unified recommendations for use of certain metrics were previously established, successful utilization in clinical practice remains relatively low, perhaps due in part to a “lack of clear and agreed-upon glycemic targets,” the report said.
In February 2019, the Advanced Technologies & Treatments for Diabetes Congress convened an international panel of patients, clinicians, and researchers with expertise in continuous glucose monitoring technologies to establish target percentages of time in the various glycemic ranges. The panel's consensus meeting was funded in part by industry, and the resulting recommendations were published online on June 8 by Diabetes Care. The report was endorsed by the American Diabetes Association, the American Association of Clinical Endocrinologists, and several other diabetes professional organizations.
The panel conducted analyses using datasets from four randomized trials, which suggested that 70% and 50% of time per day within target glucose range strongly corresponded with HbA1c levels of about 7% and 8%, respectively. A 10% increase in time per day spent in target range (2.4 h/d) corresponded to a decrease in HbA1c of about 0.5%.
The report recommended daily continuous glucose monitoring-based targets for the following populations.
- Adults with type 1 and type 2 diabetes: >70% time in target range (70 to 180 mg/dL [3.9 to 10.0 mmol/L]), <25% time above 180 mg/dL (10.0 mmol/L), <5% time below 70 mg/dL (3.9 mmol/L)
- Older/high-risk patients with type 1 and type 2 diabetes: >50% time in target range (70 to 180 mg/dL [3.9 to 10.0 mmol/L]), <50% time above 180 mg/dL (10.0 mmol/L), <1% time below 70 mg/dL (3.9 mmol/L)
- Pregnant women with type 1 diabetes: >70% time in target range (63 to 140 mg/dL [3.5 to 7.8 mmol/L]), <25% time above 140 mg/dL (7.8 mmol/L), <5% time below 63 mg/dL (3.5 mmol/L)
- Pregnant women with gestational and type 2 diabetes: Percentages of time in range not included due to very limited evidence
The report goes on to state that continuous glucose monitoring-based glycemic targets must be personalized to meet the needs of each individual with diabetes. “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 A1C for a wide range of people with diabetes and that the target values specified in this article should be considered an integral component of [continuous glucose monitoring] data analysis and day-to-day treatment decision making,” the consensus group wrote.