Practical Challenges of Switching and Cross-Titration Between Incretin-Based Therapies in Type 2 Diabetes and Obesity: A Narrative Review

Glucagon-like peptide-1 (GLP-1) receptor agonists and the dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptor agonist tirzepatide have transformed the treatment of type 2 diabetes mellitus (T2DM) and obesity. Although these agents share an incretin-based mode of action, they differ in structure, receptor pharmacology, pharmacokinetics, formulation, and titration schedule, and the individual treatment response is highly heterogeneous. Switching between agents occurs in roughly one in four to one in three patients in real-world practice, yet no standardized protocol exists: recommendations rest largely on expert consensus, and no official dose-equivalence chart has been issued. This narrative review critically evaluates evidence for switching and cross-titration between incretin-based therapies; summarizes, insofar as they inform switching decisions, the pharmacological diversity and response heterogeneity that motivate switching; and translates the evaluated evidence into a stepwise practical switching algorithm, developed by the authors as an evidence-informed expert synthesis that has not been formally validated. Special populations, persistence, discontinuation, weight regain, and the emerging pipeline of multi-agonists and oral small molecules are addressed where they modify switching decisions. Until the evidence matures, individualized reason-specific transitions that preserve the continuity of incretin-based therapy offer the most defensible framework for practice.