OFF-LABEL USE AND ADHERENCE TO GLP-1S AS ADJUNCT THERAPY IN TYPE 1 DIABETES: A COMPARATIVE ANALYSIS VERSUS METFORMIN
Author(s)
Harry Gyimah Gyamfi, MSc1, Oliver Titus, MS2, Robert Valuck, PhD RPh1, Heather Anderson, MS, PhD1;
1University of Colorado School of Pharmacy, Aurora, CO, USA, 2Univeristy of Colorado School of Pharmacy, Aurora, CO, USA
1University of Colorado School of Pharmacy, Aurora, CO, USA, 2Univeristy of Colorado School of Pharmacy, Aurora, CO, USA
OBJECTIVES: Adherence to Glucagon Like Peptide-1 receptor agonists (GLP-1s) remains underexplored in type 1 diabetes (T1D) despite increasing off-label use. This study compared adherence to GLP-1s versus metformin as adjunct therapies in T1D and examined treatment switching patterns and endocrinologist visit frequency in relation to adherence
METHODS: A retrospective cohort study was conducted using the IQVIA PharMetrics Plus for Academics database from January 2017 - May 2024. Patients aged 14 years and above with T1D (ICD-10 E10) initiating a GLP-1 RA or metformin were identified following a 12-month continuous enrollment. Adherence was defined as proportion of days covered(PDC) of at least 80%. A doubly robust approach combining inverse probability weighting with modified poisson regression was used to estimate the risks of adherence.
RESULTS: The cohort included 284 GLP-1 users and 1,010 metformin users. In the adjusted model, GLP-1 users were 28% less likely to be adherent compared to metformin users (RR = 0.72; 95% CI 0.59-0.89; p = 0.002). Within the GLP-1 cohort, 20% (n = 57) of patients switched therapies, most frequently from dulaglutide (45.6%) to semaglutide (26.3%). Each additional GLP-1 switch was associated with an average 42% lower likelihood of adherence (RR = 0.58; 95% CI 0.39-0.81; p = 0.003). Median time to switching did not differ between adherent and non-adherent users (7.1 vs. 11.7 months; p = 0.44). Among patients who switched from their initial GLP-1 to another, probability of adherence decreased by 21% after the first five endocrinologist visits. No significant differences were observed between daily and weekly GLP-1dosing. Sensitivity analyses indicated moderate robustness to unmeasured confounding (E-value = 2.12).
CONCLUSIONS: Patients with T1D initiating GLP-1s were less likely to be adherent to their GLP-1 than those initiating metformin. Early non-adherence was more common among patients who later switched GLP-1 therapies, highlighting a potential early window for adherence support.
METHODS: A retrospective cohort study was conducted using the IQVIA PharMetrics Plus for Academics database from January 2017 - May 2024. Patients aged 14 years and above with T1D (ICD-10 E10) initiating a GLP-1 RA or metformin were identified following a 12-month continuous enrollment. Adherence was defined as proportion of days covered(PDC) of at least 80%. A doubly robust approach combining inverse probability weighting with modified poisson regression was used to estimate the risks of adherence.
RESULTS: The cohort included 284 GLP-1 users and 1,010 metformin users. In the adjusted model, GLP-1 users were 28% less likely to be adherent compared to metformin users (RR = 0.72; 95% CI 0.59-0.89; p = 0.002). Within the GLP-1 cohort, 20% (n = 57) of patients switched therapies, most frequently from dulaglutide (45.6%) to semaglutide (26.3%). Each additional GLP-1 switch was associated with an average 42% lower likelihood of adherence (RR = 0.58; 95% CI 0.39-0.81; p = 0.003). Median time to switching did not differ between adherent and non-adherent users (7.1 vs. 11.7 months; p = 0.44). Among patients who switched from their initial GLP-1 to another, probability of adherence decreased by 21% after the first five endocrinologist visits. No significant differences were observed between daily and weekly GLP-1dosing. Sensitivity analyses indicated moderate robustness to unmeasured confounding (E-value = 2.12).
CONCLUSIONS: Patients with T1D initiating GLP-1s were less likely to be adherent to their GLP-1 than those initiating metformin. Early non-adherence was more common among patients who later switched GLP-1 therapies, highlighting a potential early window for adherence support.
Conference/Value in Health Info
2026-05, ISPOR 2026, Philadelphia, PA, USA
Value in Health, Volume 29, Issue S6
Code
CO87
Topic
Clinical Outcomes
Topic Subcategory
Comparative Effectiveness or Efficacy
Disease
SDC: Diabetes/Endocrine/Metabolic Disorders (including obesity)