The efficacy of real-time continuous glucose monitoring (rtCGM) and intermittently-scanned continuous glucose monitoring (isCGM) in maintaining optimal glycemic control has not been well studied. We compared the effect of rtCGM and isCGM on prevention of hypoglycemia and other glycemic metrics during exercise.
In this randomized study, adults with T1D and normal awareness of hypoglycemia (GOLD score <4) participants used rtCGM (Guardian Connect Mobile, Medtronic Inc., Northridge, USA) or isCGM (Freestyle Libre, Abbott Diabetes Care, Alameda, USA) during 4 days of structured physical activity with 4 weeks of follow-up. Primary endpoints were percentage of the time spent in hypoglycemia (<3.9 mmol/L [<70 mg/dL]) and time in range (3.9-10 mmol/L [70-180 mg/dL]).
60 adults with T1D (age 38±13 years, HbA1c 62±12 mmol/mol [7.8±1.1]) were randomized to rtCGM (n=30) or isCGM (n=30). All participants completed the study. Time spent in hypoglycemia was significantly lower among rtCGM vs. isCGM participants during exercise (6.8±5.5% vs. 11.4±8.6%; p=0.0180, respectively) and throughout the post-exercise follow-up (5.3±2.5% vs. 7.3±4.4%, p=0.0353, respectively). The differences in overnight hypoglycemia (00:00-06:00) were most notable during (7.7±11.4% vs. 20.1±18.0%, p=0.0022, respectively) and post-exercise follow=up (4.9±3.3% vs. 8.9±8.3%, p=0.0192, respectively). rtCGM participants spent significantly more time in range compared with isCGM users throughout the entire study period (76.4±8.7% vs. 67.9±15.4%, p=0.0117, respectively).
Use of rtCGM was more effective than isCGM in preventing of hypoglycemia and improving time in range in T1D participants with normal awareness of hypoglycemia, demonstrating the value of rtCGM alarms during exercise and in daily diabetes self-management.