Oral Semaglutide Reduces Heart Failure Risk in Type 2 Diabetes: SOUL Trial
In a groundbreaking secondary analysis of the SOUL randomized clinical trial, oral semaglutide has been linked to a reduced risk of heart failure events specifically in type 2 diabetes patients with pre-existing heart failure. Published in JAMA Internal Medicine, these findings provide crucial insights into the cardiovascular benefits of this GLP-1 receptor agonist (GLP-1 RA), particularly at the intersection of type 2 diabetes and heart failure—a major public health concern.
The Growing Challenge of Type 2 Diabetes and Heart Failure
Individuals with type 2 diabetes face a substantially elevated risk of developing heart failure, and when both conditions coexist, outcomes are often poorer. GLP-1 RAs like semaglutide have gained prominence for managing blood sugar levels and reducing major adverse cardiovascular events (MACE), which include cardiovascular death, nonfatal heart attack, and nonfatal stroke. However, the precise effects on heart failure outcomes have remained under investigation until now.
The SOUL trial originally demonstrated cardiovascular benefits of oral semaglutide in people with type 2 diabetes and either atherosclerotic cardiovascular disease or chronic kidney disease. This secondary analysis builds on that foundation by focusing on heart failure outcomes and exploring variations based on baseline heart failure status.
Key Details of the SOUL Trial Analysis
The study drew from data on over 9,600 participants, with nearly 25% having a history of heart failure at baseline. Conducted across 444 sites in 33 countries, the trial randomly assigned nearly 10,000 individuals aged 50 or older—with type 2 diabetes (hemoglobin A1c between 6.5% and 10%) and conditions like coronary artery disease, cerebrovascular disease, symptomatic peripheral artery disease, or chronic kidney disease—to receive either oral semaglutide or placebo, alongside standard care. The median follow-up was 49.5 months, with an average participant age of 66.1 years. Those with end-stage kidney disease or on long-term kidney replacement therapy were excluded.
Primary Findings on Heart Failure Outcomes
Among participants with existing heart failure, oral semaglutide was associated with a significantly lower risk of a composite heart failure outcome: heart failure hospitalization, urgent heart failure visits, or cardiovascular death. Importantly, this reduction was not observed in those without heart failure at trial start, indicating semaglutide's benefits are most pronounced in those already affected rather than as primary prevention.
Subgroup Insights: HFpEF vs. HFrEF
Further breakdowns showed greater reductions in heart failure events for patients with heart failure with preserved ejection fraction (HFpEF) compared to heart failure with reduced ejection fraction (HFrEF). Ejection fraction measures the heart's blood-pumping efficiency per contraction. HFpEF, characterized by a stiff heart muscle that impairs filling, currently has limited treatment options, making these results especially promising. While not all subgroups reached statistical significance, they align with emerging data on GLP-1 RAs in HFpEF.
How Oral Semaglutide Works: Mechanisms Behind the Benefits
Semaglutide, an oral GLP-1 RA, mimics the glucagon-like peptide-1 hormone to enhance insulin secretion, suppress glucagon, slow gastric emptying, and promote satiety. These actions improve glycemic control and lead to weight loss, both critical for cardiometabolic health. In heart failure, potential mechanisms include reduced inflammation, improved endothelial function, hemodynamic effects like lowered blood pressure, and direct cardioprotective properties. While the SOUL analysis doesn't pinpoint exact pathways, it complements evidence from trials like SELECT, which explored semaglutide in obesity with prevalent heart failure.
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The consistent MACE reduction with oral semaglutide—regardless of baseline heart failure—underscores its broad cardiovascular protection, with heart failure benefits adding a targeted layer for those with established disease.
Safety Profile and Adverse Events
Critically, the heart failure risk reduction did not come at the expense of safety. Rates of serious adverse events were comparable between semaglutide and placebo groups. Common GLP-1 RA side effects like gastrointestinal issues (nausea, vomiting, diarrhea) were managed within standard care, reinforcing oral semaglutide's tolerability in this high-risk population.
Clinical Implications for Patients and Providers
These results bolster the role of GLP-1 RAs in cardiometabolic management, particularly supporting oral semaglutide for type 2 diabetes patients with heart failure to lower event risks. Patients should discuss with their healthcare providers if they qualify, considering factors like ejection fraction type and comorbidities.
Who Might Benefit Most?
- Those with type 2 diabetes and established heart failure, especially HFpEF.
- Individuals with atherosclerotic cardiovascular disease or chronic kidney disease.
- Patients seeking oral alternatives to injectables like Ozempic or Wegovy (both semaglutide-based).
Compared to other GLP-1 RAs or SGLT2 inhibitors, oral semaglutide offers convenience without injections, though head-to-head trials are needed. Tools like Shotlee can help track symptoms, side effects, or medication adherence during therapy.
What to Discuss with Your Doctor
- Baseline heart failure status and ejection fraction.
- Potential for weight loss and glycemic improvements.
- Monitoring for gastrointestinal tolerance and renal function.
Key Takeaways from the SOUL Trial
- Oral semaglutide reduces composite heart failure outcomes in type 2 diabetes patients with pre-existing heart failure.
- Benefits appear stronger in HFpEF than HFrEF.
- No increased safety risks; MACE reductions persist across groups.
- Supports expanded use in cardiometabolic disease management.
Limitations and Future Research
While promising, the study calls for more research on mechanisms and optimal strategies for heart failure subtypes. Ongoing trials will clarify long-term effects and comparisons with other therapies.
Conclusion: Actionable Insights for Better Heart Health
The SOUL trial secondary analysis, led by Pop-Busui R et al. (JAMA Intern Med. DOI:10.1001/jamainternmed.2025.7774), affirms oral semaglutide's value in reducing heart failure risks for type 2 diabetes patients with the condition. Patients and clinicians should leverage these findings to personalize treatment, prioritizing discussions on GLP-1 RA integration. Stay informed on evolving cardiometabolic therapies for optimal outcomes.
Reference: Pop-Busui R et al. Oral semaglutide and heart failure outcomes in persons with type 2 diabetes: a secondary analysis of the SOUL randomized clinical trial. JAMA Intern Med. DOI:10.1001/jamainternmed.2025.7774.
