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Glycemic Outcomes of Use of CLC vs PLGS in Type 1 Diabetes: A Randomized, Controlled Trial

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posted on 29.05.2020 by Sue A. Brown, Roy W. Beck, Dan Raghinaru, Bruce A. Buckingham, Lori M. Laffel, R. Paul Wadwa, Yogish C. Kudva, Carol J. Levy, Jordan E. Pinsker, Eyal Dassau, Francis J. Doyle III, Louise Ambler-Osborn, Stacey M. Anderson, Mei Mei Church, Laya Ekhlaspour, Gregory P. Forlenza, Camilla Levister, Vinaya Simha, Marc D. Breton, Craig Kollman, John W. Lum, iDCL Trial Research Group
Background: Limited information is available about glycemic outcomes with closed-loop control (CLC) compared with predictive-low glucose suspend (PLGS).

Methods: After 6 months of use of a CLC system in a randomized trial, 109 participants with type 1 diabetes (age range 14 to 72 years, mean HbA1c 7.1% [54 mmol/mol]) were randomly assigned to CLC (N=54, Control-IQ) or PLGS (N=55, Basal-IQ) for 3 months. Primary outcome was CGM-measured time in range (TIR 70-180mg/dL). Baseline CGM metrics were computed from the last 3 months of the preceding study.
Results: All 109 participants completed the study. Mean±SD TIR was 71.1±11.2% at baseline and 67.6±12.6% using intent-to-treat analysis (69.1±12.2% using per-protocol analysis excluding periods of study-wide suspension of device use) over 13 weeks on CLC versus 70.0±13.6% and 60.4±17.1% on PLGS (difference = +5.9%, 95%CI +3.6 to +8.3; P<0.001]). Time >180mg/dL was lower in the CLC group than PLGS group (difference = -6.0%, 95%CI -8.4 to -3.7, p<0.001]) while time <54 mg/dL was similar (0.04%, 95% CI -0.05% to +0.13%; P=0.41). HbA1c after 13 weeks was lower on CLC than PLGS (7.2% [55 mmol/mol] versus 7.5% [56 mmol/mol], difference -0.34% [-3.7 mmol/mol], 95% CI -0.57 [-6.2 mmol/mol] to -0.11% [1.2 mmol/mol]; P=0.0035).
Conclusion: Following 6 months of CLC, switching to PLGS reduced TIR and increased HbA1c towards their pre-CLC values while hypoglycemia remained similarly reduced with both CLC and PLGS.


NIH/NIDDK grant UC4 108483. The University of Virginia Strategic Investment Fund Project #88 provided institutional and regulatory support. Tandem Diabetes Care provided the experimental closed-loop systems used in the trial, system-related supplies including the Dexcom CGM and Roche glucometer, and technical expertise. Tandem Diabetes Care was not involved in data analysis and was provided a copy of the manuscript for review prior to publication.