Short-Term Glycemic Response to Tirzepatide According to Prior Incretin Therapy in Patients with Type 2 Diabetes Mellitus

AimsThe aim of this study is to evaluate the short-term real-world glycemic response to tirzepatide according to prior incretin therapy in patients with type 2 diabetes mellitus (T2DM). MethodsWe retrospectively analyzed 114 patients with T2DM who initiated tirzepatide and had HbA1c measurements at baseline and three months.Patients were classified as incretin-naïve (G1, n=24), switched from dipeptidyl peptidase-4 (DPP-4) inhibitors (G2, n=24), or switched from glucagon-like peptide-1 receptor agonist (GLP-1RA)-based therapy (G3, n=66).Changes in HbA1c (ΔHbA1c) were compared among groups, and factors associated with ΔHbA1c were evaluated using multivariable linear regression. ResultsThe overall median ΔHbA1c was -0.8% [interquartile range: -1.4 to -0.4] (P<0.001), with significant reductions in all three groups.ΔHbA1c differed significantly among groups (P=0.023), with a significant difference between G1 and G3 (P=0.034).After multivariable adjustment, G3 had a smaller HbA1c reduction than G1 (B=0.763,95% CI: 0.367 to 1.158; P<0.001). ConclusionsTirzepatide initiation was associated with improved glycemic control across all prior incretin therapy groups.However, the magnitude of HbA1c reduction varied according to prior incretin therapy, with a smaller adjusted reduction in patients switched from GLP-1RA-based therapy than in incretin-naïve patients.These findings reflect the early treatment phase, during which some patients had not yet reached a maintenance dose, and may not represent longer-term glycemic responses.