BACKGROUND: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are widely used therapies for cardiovascular risk reduction in type 2 diabetes (T2D). With the emergence of the SURPASS-CVOT trial, tirzepatide (a dual GIP/GLP-1 receptor agonist) has entered the therapeutic landscape; however, its comparative effect on cardiovascular outcomes compared to placebo and individual GLP-1RAs remains undefined.
METHODS: We conducted a systematic review and frequentist network meta-analysis (NMA) of RCTs enrolling adults with type 2 diabetes (T2D) and established atherosclerotic cardiovascular disease (ASCVD) or high cardiovascular (CV) risk. Eligible RCTs evaluated tirzepatide or GLP-1RAs and reported major adverse cardiovascular events (MACE), CV mortality, all-cause mortality, non-fatal myocardial infarction (MI) or non-fatal stroke. A class-level NMA was conducted to estimate the incremental benefit of tirzepatide and GLP-1RAs over placebo, and an agent-level NMA was conducted to explore differences between tirzepatide and individual GLP-1RA agents. Subgroup analyses, including established cardiovascular disease populations, and leave-one-out sensitivity analyses were performed.
RESULTS: Eleven trials met inclusion criteria (10 GLP-1RA trials and 1 tirzepatide trial [SURPASS-CVOT]). In the class-level analysis, tirzepatide significantly reduced MACE (HR 0.79, 95% CI 0.69-0.91), CV mortality (HR 0.77, 95% CI 0.66-0.90), all-cause mortality (HR 0.74, 95% CI 0.65-0.83), non-fatal MI (HR 0.77, 95% CI 0.61-0.97), and non-fatal stroke (HR 0.79, 95% CI 0.64-0.97) compared to placebo. Formal statistical comparisons between tirzepatide and the GLP-1RA class could not be performed within the constraints of the NMA; however, point estimates across outcomes numerically favored tirzepatide compared with placebo. In the agent-level analysis, tirzepatide reduced MACE compared to placebo (HR 0.81, 95% CI 0.70-0.94) and lixisenatide (HR 0.79, 95% CI 0.65-0.97). Subgroup and sensitivity analyses did not substantially change point estimates.
CONCLUSION: Among adults with T2D and established ASCVD or high CV risk, class-level analysis demonstrated that tirzepatide significantly reduced the risk of cardiovascular events compared to placebo; at the agent-level, tirzepatide demonstrated comparable efficacy to individual GLP-1RAs. These findings suggest that tirzepatide provides cardiovascular benefit at least comparable to established GLP-1RAs, supporting its emerging role in cardiovascular risk reduction in T2D.
