19-PUB: Real-World Outcomes of Adjunct GLP-1 Receptor Agonist Therapy in Adults with Type 1 Diabetes: A Retrospective Cohort Study

Introduction and Objective: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are approved for the treatment of type 2 diabetes and obesity. Off-label use of GLP-1RA for type 1 diabetes (T1DM) is increasingly considered; however, evidence supporting adjunctive use with insulin remains limited. This study evaluated real-world glycemic, metabolic, and safety outcomes of adjunctive GLP-1RA therapy compared with insulin alone. Methods: We conducted a retrospective cohort study using de-identified EHR data from the UCSF Clinical Data Warehouse. Adults aged 18-65 years with ≥2 diagnoses of T1DM and insulin use were included; patients with ≥2 diagnoses of T2DM were excluded. Exposure groups were insulin alone or insulin plus GLP-1RA; the insulin-only group substantially outnumbered the GLP-1RA group, reflecting real-world prescribing patterns. The index date was insulin initiation. The primary outcome was mean change in point-of-care hemoglobin A1c from baseline (within 90 days pre-index) to 3 months post-index. Secondary outcomes included changes in BMI, body weight, and safety events (diabetic ketoacidosis and hypoglycemia) within a 6-month period. Continuous outcomes were analyzed using Welch two-sample t-tests and categorical outcomes using Fisher’s exact test. Analyses were conducted using SQL-based extraction with patient-level linkage. Results: Fourteen patients received insulin plus GLP-1RA and 323 received insulin alone. Mean A1c reduction (percent) was greater with insulin plus GLP-1RA (−0.72% vs −0.26%), though not statistically significant (mean difference −0.46%; 95% CI −1.29 to 0.37; p=0.30). No significant differences in BMI or weight change were observed. No diabetic ketoacidosis or hypoglycemia events occurred in the GLP-1RA group. Conclusion: In this real-world cohort, adjunctive GLP-1RA therapy was associated with a numerically greater A1c reduction without an increase in adverse events. However, the results were limited by the small sample size and the availability of data. Larger multicenter studies are needed to better define the role of GLP-1RAs in type 1 diabetes mellitus (T1DM). Disclosure S. Lin: None. M. Nevarez: None. E. Hu: None. G. Chen: None.