646-P: Sustained Impact of Switching from Intermittently Scanned to Real-Time Continuous Glucose Monitoring in Adults with Type 1Diabetes: 24-Month Results of the ALERTT1 Trial
Authors: VISSER MARGARETHA M. , CHARLEER SARA , FIEUWS STEFFEN , DE BLOCK CHRISTOPHE , HILBRANDS ROBERT , VAN HUFFEL LIESBETH , MAES TOON , VANHAVERBEKE GERD , DIRINCK EVELINE L. , MYNGHEER NELE , VERCAMMEN CHRIS F. , NOBELS FRANK , KEYMEULEN BART , MATHIEU CHANTAL , GILLARD PIETER 
Published: May 2022

Background: The 6-month multicenter randomized controlled ALERTT1 trial showed improvement of time in range (TIR; 70-180 mg/dL) , HbA1c, time &lt;54 mg/dL and fear of hypoglycemia in adults with type 1 diabetes (T1D) switching from intermittently scanned continuous glucose monitoring (isCGM; FreeStyle Libre 1) to real-time CGM (rtCGM; Dexcom G6) . It is unclear whether these benefits are sustained in the long term.
Methods: In this partial cross-over extension trial, the control group (n=127) switched as planned from isCGM to rtCGM from month 6 to month 24. The experimental group (n=127) continued rtCGM until month 24. Primary outcome was TIR. Key secondary outcomes were HbA1c, time &lt;54 mg/dL and Hypoglycemia Fear Survey worry (HFS-worry) score. Within-group change (Δ) vs. start of rtCGM is reported (mean [95% CI]) .
Results: People in the trial were on average 42.9 years old; mean HbA1c was 7.4%. A minority used an insulin pump (n=49) or were hypo unaware (n=44) . TIR increased from 51.8% to 63.5% at month 12 in the former isCGM group (Δ 11.7% [9.6-13.8] P&lt;0.0001) and remained stable up to month 24 (Δ 11.7% [9.4-14.0] P&lt;0.0001) . In the former rtCGM group, TIR increased from 52.5% to 63.0% at month 12 (Δ 10.6% [8.4-12.8] P&lt;0.0001) and remained stable up to month 24 (Δ 10.5% [8.2-12.8] P&lt;0.0001) . HbA1c decreased to 6.9% (Δ -0.54%; P&lt;0.0001) and 7.0% (Δ -0.43%; P&lt;0.0001) at month 24 in the former isCGM and rtCGM group respectively, together with a decrease of -2.67 points (P=0.0008) and -5.17 points (P&lt;0.0001) in HFS-worry score. No significant reduction in time &lt;54 mg/dL was seen after month 12. Percentage of people achieving the TIR consensus target increased from 14.9% to 37.8% (P&lt;0.0001) in the former isCGM group and from 13.4% to 41.4% (P&lt;0.0001) in the former rtCGM group.
Conclusion: In adults with T1D, switching from isCGM to rtCGM is beneficial up to 24 months, adding further evidence that rtCGM with alerts is superior to isCGM without alerts.

Disclosure
M.M.Visser: Other Relationship; Boehringer Ingelheim International GmbH, Dexcom, Inc., Dexcom, Inc., Novo Nordisk. N.Myngheer: Advisory Panel; AstraZeneca, Speaker's Bureau; AstraZeneca, Novo Nordisk. C.F.Vercammen: Other Relationship; AstraZeneca. F.Nobels: Advisory Panel; Abbott Diabetes, AstraZeneca. B.Keymeulen: None. C.Mathieu: Advisory Panel; Abbott, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Imcyse, Insulet Corporation, Medtronic, Novo Nordisk, Sanofi, Zealand Pharma A/S, Speaker's Bureau; AstraZeneca. P.Gillard: Advisory Panel; Bayer AG, Novo Nordisk, Speaker's Bureau; Abbott Diabetes, Bayer AG, Dexcom, Inc., Insulet Corporation, Medtronic, Novo Nordisk, Roche Diabetes Care, Sanofi. S.Charleer: None. S.Fieuws: None. C.De block: Advisory Panel; Abbott Diagnostics, AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Medtronic, Novo Nordisk, Research Support; Indigo Diabetes, Speaker's Bureau; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Novo Nordisk. R.Hilbrands: None. L.Van huffel: Advisory Panel; Roche Diagnostics, Other Relationship; Medtronic, Speaker's Bureau; Abbott Diabetes, AstraZeneca, Boehringer Ingelheim International GmbH, Merck Sharp & Dohme Corp., Novo Nordisk. T.Maes: None. G.Vanhaverbeke: Advisory Panel; Abbott Diabetes, AstraZeneca, Boehringer Ingelheim International GmbH, Lilly Diabetes, Merck Sharp & Dohme Corp., Speaker's Bureau; Novo Nordisk, Sanofi. E.L.Dirinck: None.

Funding
Dexcom, San Diego, CA, USA (OUS-2018-011)