Investigators are building an empirical evidence base for real world data through large-scale emulation of randomized controlled trials. The investigators' goal is to understand for what types of clinical questions real world data analyses can be conducted with confidence and how to implement such studies.

This is a non-randomized, non-interventional study that is part of the Randomized Controlled Trials Duplicated Using Prospective Longitudinal Insurance Claims: Applying Techniques of Epidemiology (RCT-DUPLICATE) initiative (www.rctduplicate.org) of the Brigham and Women's Hospital, Harvard Medical School. It is intended to assess the comparative effectiveness of tirzepatide vs sitagliptin as a placebo proxy, after the pivotal RCT SURPASS-CVOT (NCT04255433) and its emulation (NCT07088718) demonstrated non-inferiority, leaving both regulators and clinical guideline committees uncertain whether to approve and recommend tirzepatide for a cardiovascular indication. This comparative effectiveness target trial described below draws from eligibility criteria from the SURPASS-CVOT trial and its emulation. Although many features of the target trial cannot be directly replicated in healthcare claims, key design features, including outcomes, exposures, and inclusion/exclusion criteria, were selected to proxy those features from the target trial. Randomization cannot be achieved in healthcare claims data but was proxied through a statistical balancing of measured covariates according to standard practice.

The purpose of this protocol is to specify the target trial assessing the comparative effectiveness of the dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 receptor agonist (GLP-1-RA) tirzepatide vs the dipeptidyl peptidase-4 inhibitors (DPP4i) sitagliptin on atherosclerotic cardiovascular end points in patients with type 2 diabetes and atherosclerotic cardiovascular disease.

The database study will be a new-user active-comparative study, conducted using 2 national United States claims databases, where we compare the effect of tirzepatide vs sitagliptin in preventing atherosclerotic cardiovascular events. Clinical guidelines during the study period recommended both agents under investigation as second-line options for glucose lowering and were similarly costly.

Inclusion Criteria:

• History of MI or stroke, surgical or percutaneous coronary/carotid peripheral artery revascularization, amputation, diagnosis of coronary/carotid/peripheral artery disease
• BMI ≥25.0kg/m2
• Type 2 diabetes
• Age ≥40 years
• Male or female sex

Exclusion Criteria:

• Medullary thyroid carcinoma, MEN syndrome type 2, malignancy
• Treatment for diabetic retinopathy/macular edema, heart failure NYHA IV, gastric emptying abnormality/bariatric surgery, end-stage renal disease or dialysis, pregnancy
• Prior use of pramlintide or any GLP-1-RA except tirzepatide,
• Pancreatitis, liver disease
• Cardiovascular event or intervention, hospitalization for heart failure
• Concurrent use of both drugs i.e. tirzepatide and sitagliptin

Individuals aged 40 years or older with T2DM and and atherosclerotic cardiovascular disease.