Changes in HbA1c With Glucagon-Like Peptide-1 Receptor Agonist Therapy Alone and Followed by Initiation of Continuous Glucose Monitoring: A Retrospective Analysis of U.S. Medical Claims Data

BACKGROUND: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and continuous glucose monitors (CGMs) can each improve glycemic control. This retrospective cohort study evaluates the effect of a CGM in patients with type 2 diabetes (T2D) already receiving GLP-1 RAs. METHODS: This study analyzed IQVIA's US medical and pharmacy claims data between January 2019 and December 2023. Two distinct cohorts of patients with T2D were included. The first comprised patients initiating a GLP-1 RA (GLP-1 RA cohort). The second comprised patients on a GLP-1 RA who subsequently started using a CGM (GLP-1 RA + CGM cohort). Propensity score matching of clinical and demographic factors was used to control confounding between groups. Changes in glycated hemoglobin (HbA1c) were assessed quarterly over 12 months; mixed-effects logistic regression was used to assess the impact of time and CGM use. A subgroup analysis was performed based on the duration of GLP-1 RA exposure prior to CGM initiation. RESULTS: The final matched sample included 13 221 patients. Both cohorts showed HbA1c reduction, but the GLP-1 RA + CGM cohort demonstrated a faster and more substantial decrease. At 12 months, 31% of GLP-1 RA + CGM patients versus 44% of GLP-1 RA-only patients had HbA1c >9%, while 23% versus 20% achieved HbA1c <7%, respectively. Regression modeling confirmed significantly greater odds for HbA1c reduction with CGM use, which held true across subgroups. CONCLUSIONS: Adding CGM to GLP-1 RA therapy accelerates and enhances glycemic improvement compared with GLP-1 RA alone, regardless of prior GLP-1 RA duration. These findings support combined use to optimize T2D management and reduce time with poor glycemic control.