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ALERTT1 Follow-up Study Highlights Significant rtCGM Results After 24 Months Use

Published on: 1 June 2023

medical staff entering data, stethoscope in foreground

The 2021 ALERTT1 trial concluded that switching from intermittently-scanned continuous glucose monitoring (isCGM) to real-time CGM (rtCGM) significantly improved time in range (TIR), A1C, and time in hypoglycemia for adults living with type 1 diabetes after 6 months of use.1

The results from the extension of the trial published in 2023 show that 24 months of rtCGM use yields significant results compared to isCGM, including improved glycemic control and reduced fear of hypoglycemia.2

2021 Trial Proved Benefits of rtCGM Use

The 2021 ALERTT1 trial assessed 246 adult participants with type 1 diabetes (T1D) who had been using the FreeStyle Libre isCGM device for at least 6 months. Half of the participants were randomized to switch to a Dexcom rtCGM device with predictive alerts, and the remainder continued using isCGM. After 6 months, various outcomes in the two groups were compared.

The results of the trial showed significant improvements in A1C levels, time in range, and hypoglycemia after switching to rtCGM:1

  • 48% of participants reached an A1C lower than 7% without severe hypoglycemia, compared to 32% of the isCGM group (P=0.0004).
  • Participants experienced 6.85% more time spent in their target glucose range than those on isCGM. 
  • Participants scored 2.62 less percentage points on the Hypoglycemia Fear Survey version II worry subscale.

Alerts and alarm functionality played an important role in these results. An rtCGM device like the Dexcom G6 rtCGM System features a predictive Urgent Low Soon alert so patients can take preventative action before glucose levels are dangerously low. This may have allowed participants who previously had no alerts with a FreeStyle Libre isCGM system to manage their condition better and feel more in control of their glucose. 

Download an ALERTT1 study summary

Trial Extension Shows Sustained Benefits Over 24 Months 

The 2021 ALERTT1 trial validated the importance of rtCGM for diabetes care, and the 2023 extension further demonstrated that the benefits are sustained over a two-year period. 

In the trial extension, isCGM users switched to using an rtCGM device after the initial 6-month trial period. This group is referred to as the is-rtCGM group. The original intervention group remained on rtCGM and is referred to as the rt-rtCGM.

Significant improvements were seen in the is-rtCGM group:2

  • TIR increased at the 12-month and 18-month marks after the switch to rtCGM at month 6, and then remained stable from the 18 to 24-month marks (P<0.0001).
  • A1C significantly improved from 7.4% at month 6 before switching to rtCGM, to 6.9% at month 24 after 18 months on rtCGM (P<0.0001).
  • Fear of hypoglycemia dropped by 2.67 survey points in month 24 compared to month 6 (P=0.0008).
  • Severe hypoglycemia decreased from 31·0 to 3·3 per 100 patient-years after switching to rtCGM.

The results provide additional, long-term evidence that switching from isCGM without alerts to an rtCGM system with predictive alerts can significantly improve glycemic control over an extended period.

Read the ALERTT1 trial extension

Other Clinical Studies Show Similar Results

A 2022 study used the Canadian LMC Diabetes Registry to assess real-world clinical outcomes of rtCGM use at 6–12 months in adults with type 1 diabetes (T1D). 1,612 participants were split into matched cohorts of isCGM and rtCGM users.

The study found that rtCGM allowed participants to achieve significantly lower A1C levels, more time in range, lower glycemic variability, and less time in hypoglycemia compared to isCGM. 

Review the REAL-CGM-T1D study

Prescribe Dexcom G6 to Put Results into Practice 

Studies like ALERTT1 and REAL-CGM-T1D show how powerful rtCGM can be in improving the health and quality of life of people living with diabetes, empowering them to better manage their condition in their daily lives. 

Getting your patients started on the Dexcom G6 rtCGM System today is easy. Learn more about available healthcare coverage or contact our dedicated team of specialists for support and sample requests.

Prescribe now

1 Visser MM, et al. Lancet 2021;397(10291):2275-83.
2 Visser MM, et al. Lancet 2023;11(2):96-108.
3 Brown R, et al. Diabetic Medicine. 2022;39(11):e14937.

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