Association of Changes in A1C Following Continuous Glucose Monitoring Acquisition in People with Sub-Optimally Treated Type 2 Diabetes Taking GLP-1 RA Therapy.

ABSTRACT

INTRODUCTION: Both glucagon-like peptide-1 receptor agonists (GLP-1 RA) and continuous glucose monitoring (CGM) improve glycemia in patients with type 2 diabetes (T2D). However, it is unknown whether adding CGM to GLP-1 RA therapy further improves A1c. We evaluated changes in A1c levels 6 months after initiation of FreeStyle Libre (FSL) in adults with sub-optimally controlled T2D already on GLP-1 RA therapy. METHODS: This retrospective, observational study used Optum's de-identified Market Clarity Data, a linked electronic health record-claims database to assess changes in A1c after FSL acquisition. Inclusion criteria were T2D diagnosis, ≥ 18 years, baseline A1c ≥ 8%, with the first FSL acquisition between 2018 and 2022. Patients were required to be on GLP-1 RA prior to FSL with at least one GLP-1 RA prescription within 90 days of FSL acquisition. GLP-1 RA initiation was defined as the earliest GLP-1 RA prescription from 2017 onwards. Paired changes in A1c were assessed at 6 months after initial FSL acquisition. RESULTS: The study cohort included 1454 adults with T2D (age 55 ± 10 years, 52% male, 38% with intensive insulin therapy, median 471 days from GLP-1 RA initiation to FSL, and baseline A1c 9.8 ± 1.5%). After FSL acquisition, patients experienced an A1c decrease of 1.5 ± 1.9% (p < 0.001). Patients with a baseline A1c > 10% had the largest reduction (n = 497, - 2.7 ± 2.2%, p < 0.001). Significant improvements were observed in subgroups based on insulin therapy and GLP-1 RA formulation. Those initiating GLP-1 RA therapy > 24 months before FSL acquisition also showed improvements in A1c (n = 478; - 1.3 ± 1.7%, p < 0.001). CONCLUSIONS: In a large, real-world study of adults with T2D, those on prior GLP-1 RA therapy experienced significant A1c improvements after acquiring FSL, irrespective of GLP-1 RA duration, GLP-1 RA formulation, or insulin therapy type. These findings support the use of FSL in adults with T2D treated with GLP-1 RA.