Cardioprotective Effects of SGLT2 Inhibitors and GLP-1 Receptor Agonists in Korean Patients With Type 2 Diabetes

This is an investigator-initiated, two-phase observational study integrating a multicenter retrospective cohort analysis with a single-center prospective validation cohort. The two phases involve different study populations and data sources and will be analyzed independently. Their findings will be interpreted together to provide complementary evidence regarding long-term clinical cardiovascular outcomes and short-term changes in cardiac function among Korean patients with type 2 diabetes.

In Phase 1, de-identified electronic health record data mapped to the Observational Medical Outcomes Partnership Common Data Model will be obtained from participating Korean hospitals through a distributed data network. A new-user, active-comparator cohort design will be used to compare patients initiating an SGLT2 inhibitor with those initiating a GLP-1 receptor agonist. Medication exposure, cardiovascular events, safety outcomes, metabolic measures, and treatment patterns will be identified using prespecified common data model definitions. Confounding will be addressed using propensity score methods, stratified analyses, and sensitivity analyses. Participating institutions will execute a common analytic protocol locally and provide only aggregated, non-identifiable results for multicenter analysis.

In Phase 2, adults with type 2 diabetes who are scheduled to start an SGLT2 inhibitor during routine clinical care at Dongtan Sacred Heart Hospital will be consecutively screened. Baseline assessments will include standard 12-lead electrocardiography, portable 6-lead electrocardiography, AI-based ECG analysis, advanced echocardiography, laboratory testing, body composition assessment, and research blood sampling. Participants will be classified according to prespecified echocardiographic criteria for stage B heart failure. Approximately 50 participants who meet the protocol-defined criteria for the longitudinal cohort will undergo repeat assessments 6 months after baseline. Baseline data from other consented screening participants may be included in cross-sectional analyses.

Phase 2 will evaluate whether AI-based ECG measurements reflect echocardiographic cardiac dysfunction at baseline and whether changes in AI-based ECG measurements correspond to changes in cardiac function after SGLT2 inhibitor treatment. Analyses will focus on changes within participants, correlations and agreement between AI-ECG and echocardiographic measurements, and the feasibility of AI-ECG for monitoring subclinical cardiac dysfunction.

Medication selection, dose, continuation, and modification are determined solely by the treating physicians according to routine clinical practice. The protocol does not assign treatment, require medication changes, or use AI-ECG results to guide clinical care. No individual-level data will be combined across Phase 1 and Phase 2.

Phase 1: Retrospective Cohorts

Inclusion criteria

• Adults aged 19 years or older.
• Diagnosis of type 2 diabetes mellitus.
• New initiation of a study medication, including an SGLT2 inhibitor, a GLP-1 receptor agonist, or another eligible glucose-lowering medication.
• At least 180 days of observable data before the index date, defined as the date of the first eligible prescription.

Exclusion criteria

• Type 1 diabetes mellitus or secondary diabetes mellitus.
• Use of a medication from the same drug class within 90 days before the index date.
• Pregnancy recorded during the relevant study period.
• A history of the outcome being evaluated during the baseline period, applied separately for each outcome analysis.

Phase 2: Prospective SGLT2 Inhibitor Validation Cohort

Inclusion criteria

• Adults aged 50 years or older receiving outpatient care at Dongtan Sacred Heart Hospital.
• Diagnosis of type 2 diabetes mellitus.
• No current or previous signs or symptoms of heart failure and New York Heart Association functional class I.
• At least one of the following high-risk characteristics: diabetes duration of 5 years or longer, hypertension, body mass index of 25 kg/m² or higher, urinary albumin-to-creatinine ratio of 30 mg/g or higher, estimated glomerular filtration rate below 60 mL/min/1.73 m², or diabetic microvascular complications.
• No previous treatment with an SGLT2 inhibitor and scheduled to initiate an SGLT2 inhibitor based on the treating physician's clinical judgment.
• Ability and willingness to provide written informed consent.

Exclusion criteria

• Current or previous diagnosis of heart failure, hospitalization for heart failure, clinically suspected signs or symptoms of heart failure, or screening left ventricular ejection fraction below 50%.
• Moderate or severe valvular heart disease, known hypertrophic, dilated, or infiltrative cardiomyopathy, complex congenital heart disease, or clinically significant pericardial disease.
• Acute coronary syndrome, coronary revascularization, or stroke within 3 months before enrollment.
• Presence of a pacemaker, implantable cardioverter-defibrillator, or cardiac resynchronization therapy device.
• Atrial fibrillation, sustained tachycardia, frequent premature contractions, or another arrhythmia that prevents reliable comparison of ECG or global longitudinal strain measurements.
• Type 1 diabetes mellitus, secondary diabetes mellitus, diabetic ketoacidosis within the previous year, or another clinical condition making SGLT2 inhibitor treatment inappropriate.
• Estimated glomerular filtration rate below 30 mL/min/1.73 m² or dialysis.
• Echocardiographic image quality insufficient for reliable 3-view global longitudinal strain or stage B heart failure assessment.
• Pregnancy or breastfeeding.
• Unwillingness to undergo study assessments or inability to complete the 6-month follow-up.