medwireNews: Switching from intermittently scanned to real-time continuous glucose monitoring (isCGM to rtCGM) improves time in range by a clinically relevant percentage, show the findings of the 6-month ALERTT1 trial.
The switch, among people with type 1 diabetes who had already been using isCGM for at least 6 months, also resulted in significant improvements in patient-reported outcomes, say Pieter Gillard (University Hospitals Leuven–KU Leuven, Belgium) and co-researchers.
All study participants were using the Abbott FreeStyle Libre isCGM system at baseline. Of the 127 randomly assigned to continue with this system, 122 completed the 6-month follow-up, as did 124 of the 127 assigned to switch to the Dexcom G6 rtCGM.
Time in range (3.9–10.0 mmol/L; 70–180 mg/dL) was similar in the isCGM and rtCGM groups at baseline, at 51.3% and 52.5%, respectively.
This had changed little by the 6-month follow-up in the isCGM group, at 51.9%, but it increased to 59.6% in the rtCGM group, giving a significant 6.85 percentage point difference.
In a commentary linked to the publication in The Lancet, Kirsten Nørgaard and Signe Schmidt, both from Steno Diabetes Center Copenhagen in Denmark, remark that this time in range difference “is clinically relevant as it is thought to result in a 10–25% relative risk reduction in microvascular complications.”
But they add that the study design “does not inform us about whether all CGM-naive patients should start rtCGM directly or whether a stepwise approach beginning at isCGM is more sensible (ie, whether certain subpopulations will have sufficient benefit from isCGM).”
Switching to rtCGM also resulted in a significant 0.36 percentage point reduction in glycated hemoglobin versus the isCGM group, and a significant 0.35 percentage point reduction in the time spent in hypoglycemia, from 0.91% at baseline to 0.47% at follow-up, compared with 1.05% and 0.84%, respectively, with isCGM. Likewise, the rate of severe hypoglycemia was 2% in the rtCGM group versus 11% in the isCGM arm.
In addition, after 6 months rtCGM users had a significantly lower average score on the Hypoglycaemia Fear Survey version II worry subscale than the isCGM users, at 15.4 versus 18.0 (baseline scores were 18.8 vs 18.7). And participants using rtCGM also reported significantly greater treatment satisfaction than those using isCGM.
In their commentary, Nørgaard and Schmidt say the researchers “should be commended for addressing an important clinical question regarding the efficacy of two different CGM systems.”
But they add: “Nevertheless, the bearing of such findings is short lived: a new version of isCGM has already been launched and clinical testing of a new generation of rtCGM is ongoing.
“The pace of diabetes device development creates many challenges. Nonetheless, we cherish this momentum: it gives hope for a better future for diabetes care.”
The findings were also presented at the virtual ATTD 2021 conference, by lead study author Margaretha Visser (University Hospitals Leuven–KU Leuven).
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Lancet 2021; doi:10.1016/S0140-6736(21)00789-3
Lancet 2021; doi:10.1016/S0140-6736(21)01211-3