Clinical data from real-world scenarios indicates that the GLP-1 receptor agonists semaglutide and tirzepatide are effective in managing blood sugar and weight, and also demonstrate heart-protective effects that align with the outcomes observed in clinical trials involving diverse patient populations.
A recent study published in Nature Medicine compared major adverse cardiovascular events (MACE) between glucagon-like peptide-1 (GLP-1) receptor agonists and comparators, evaluating real-world estimates against randomized trial data to inform clinical decision-making.
Cardiovascular Risk and Therapeutic Relevance in Type 2 Diabetes
Adults diagnosed with type 2 diabetes are at a greater risk of myocardial infarction and stroke. Glucose-lowering medications can influence weight, blood pressure, and lipid levels, raising questions about their cardiovascular effects in routine clinical care. While randomized controlled trials provide strong evidence, they might not fully represent the older, multimorbid patient populations commonly seen in primary care settings.
Therefore, there is a need for evidence reflecting routine practice, while addressing the limitations of claims-based data, namely the potential omission of lifestyle factors like diet, smoking, or exercise. Health tracking apps like Shotlee can help monitor these lifestyle factors and their impact on diabetes management.
Study Framework and Data Sources
Researchers designed five active-comparator, new-user cohort studies utilizing three major U.S. claims databases: Medicare Parts A, B, and D (2018-2020), Optum Clinformatics Data Mart (2018-February 2025), and Merative MarketScan (2018-2023). These datasets contain de-identified longitudinal information on diagnoses, prescriptions, procedures, and healthcare usage across various populations.
The study was conducted in three phases: emulation of the SUSTAIN-6 and SURPASS-CVOT trials, expansion to real-world cohorts, and a direct comparison of tirzepatide and semaglutide. Participants included adults with type 2 diabetes and obesity, categorized by cardiovascular risk, including established cardiovascular disease, NYHA class II-III heart failure, or chronic kidney disease.
Endpoint Definitions and Statistical Approach
The primary endpoint was MACE, encompassing all-cause mortality, myocardial infarction, or stroke, assessed over 52 weeks. Propensity-score matching (1:1) was applied to balance treatment groups, and risk estimates were generated using Kaplan-Meier curves, Cox proportional hazards models, and fixed-effects meta-analysis. Concordance with randomized trials was evaluated using predefined benchmarks.
Validation Against Randomized Clinical Trials
Benchmarking analyses showed strong agreement with reference trials. In the SURPASS-CVOT emulation (tirzepatide vs dulaglutide), the hazard ratio for MACE was 0.83 (95% CI, 0.69-1.01), compared to 0.92 (95% CI, 0.83-1.01) in the trial. Similarly, the SUSTAIN-6 emulation (semaglutide vs sitagliptin) reproduced trial-aligned estimates, except for all-cause mortality, leading to methodological refinements that emphasized myocardial infarction and stroke endpoints.
Real-World Effectiveness Across Drug Comparisons
In routine-care populations, semaglutide reduced the 1-year risk of myocardial infarction or stroke to 1.5% compared to 1.7% with sitagliptin (HR, 0.82; 95% CI, 0.74-0.91). For tirzepatide versus dulaglutide, MACE risk was 1.4% versus 1.8% (HR 0.87; 95% CI, 0.75-1.01), consistent across risk groups. The head-to-head comparison of tirzepatide versus semaglutide indicated equivalent cardiovascular outcomes (HR 1.06; 95% CI, 0.95-1.18).
Secondary outcomes demonstrated that semaglutide reduced myocardial infarction (HR 0.81) and stroke (HR 0.84) compared to sitagliptin. Tirzepatide was shown to be non-inferior to dulaglutide regarding mortality, myocardial infarction, and stroke. Both GLP-1 agents showed a positive impact on composite heart-failure outcomes, with both semaglutide and tirzepatide reducing hospitalization or urgent visits.
Subgroup and Sensitivity Findings
Stratified analyses based on age, sex, SGLT2 inhibitor co-use, and cardiovascular risk showed no significant heterogeneity, supporting the external validity of the findings. Semaglutide showed a numerically lower MACE, while tirzepatide showed favorable heart failure profiles. However, limitations of claims data require mindful interpretation of causal inferences.
Implications for Clinical Practice and Policy
Semaglutide reduced MACE compared to sitagliptin in real-world care, and tirzepatide demonstrated cardiovascular effectiveness comparable to both dulaglutide and semaglutide. These findings are consistent with randomized trial evidence, reinforcing confidence that the observed benefits extend beyond controlled settings. GLP-1 receptor agonists support glycemic and weight management, while also providing significant cardiovascular protection for patients with type 2 diabetes. The findings support broader application of GLP-1 therapies to reduce cardiovascular risk in routine practice.
