BACKGROUND: Tirzepatide, a once-weekly glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonist approved for the treatment of adults with type 2 diabetes or obesity, showed clinically meaningful reductions in hemoglobin A OBJECTIVE: To compare efficacy and safety of escalation of dulaglutide dose versus switching to tirzepatide in inadequately controlled type 2 diabetes. DESIGN: Multicenter, randomized, open-label, phase 4 trial (SURPASS-SWITCH [A Phase 4, Randomized, Open-Label, Active-Controlled Study to Investigate the Efficacy and Safety of Switching from Weekly Dulaglutide to Weekly Tirzepatide in Adults with Type 2 Diabetes], ClinicalTrials.gov: NCT05564039). SETTING: 38 sites across 5 countries. PARTICIPANTS: Adults with HbA INTERVENTION: Escalation of dulaglutide to 4.5 mg or maximum tolerated dose (MTD) or switching to tirzepatide. MEASUREMENTS: The primary end point was change from baseline in HbA RESULTS: A total of 282 adults were randomly assigned to tirzepatide ( LIMITATION: Open-label design. CONCLUSION: In SURPASS-SWITCH, switching treatment to tirzepatide provided additional HbA PRIMARY FUNDING SOURCE: Eli Lilly and Company.