Oral semaglutide cuts heart attack risk by 26% - SOUL trial findings

TL;DR

The SOUL trial found oral semaglutide (Rybelsus) reduced major cardiovascular events by 14% in high-risk type 2 diabetes patients over nearly four years, driven primarily by a 26% reduction in nonfatal heart attacks. This is the first evidence that an oral GLP-1 medication matches the cardiovascular protection previously seen only with injectables.

Every injectable semaglutide user has long had a clear cardiovascular benefit backed by the SUSTAIN-6 and SELECT trials. Now, for the first time, the same benefit has been demonstrated in pill form. The SOUL trial - a large international cardiovascular outcomes trial of oral semaglutide - has answered a question that has hung over Rybelsus since its approval: does a pill that gets only a fraction of the drug into circulation actually protect the heart?

The short answer: yes. The longer answer involves important caveats that every person on GLP-1 medications should understand.

What the SOUL trial was and who was in it

SOUL enrolled 9,650 adults across 33 countries on five continents. Participants had type 2 diabetes with a median disease duration of 14.7 years, plus at least one of the following: established cardiovascular disease (atherosclerotic), cerebrovascular disease, peripheral arterial disease, or chronic kidney disease with a GFR below 60.

This was a high-risk population by design. Mean age was 66.1 years, 71.5% were male, mean BMI was 31 kg/m², and mean HbA1c was 8%. Median follow-up was 49.5 months - just over four years. All participants received either oral semaglutide (Rybelsus at the standard 14 mg dose) or placebo.

The primary outcome: a 14% reduction in major cardiovascular events

The primary endpoint was a three-point composite: nonfatal MI, nonfatal stroke, or cardiovascular death. Oral semaglutide achieved an event rate of 12% versus 13.8% in the placebo group - a hazard ratio of 0.86 (95% CI: 0.77-0.96, p=0.006). That 14% relative risk reduction crossed the threshold for statistical significance.

Breaking the composite down by component tells a more nuanced story:

• Nonfatal MI: 4.0% vs 5.2% - hazard ratio 0.74 (26% relative risk reduction) - statistically significant
• Nonfatal stroke: 3.0% vs 3.3% - no significant difference
• Cardiovascular death: 6.2% vs 6.6% - no significant difference

The benefit was almost entirely driven by fewer heart attacks. The drug did not significantly reduce stroke risk or cardiovascular mortality on its own. That is worth understanding: oral semaglutide appears to protect against ischaemic coronary events but does not - at least at the doses used in SOUL - show the broader cardiovascular mortality protection seen with injectable semaglutide in SELECT.

Secondary outcomes: what else changed

Beyond the primary endpoint, oral semaglutide produced meaningful metabolic improvements over four years:

• HbA1c reduction: -0.71% at 104 weeks
• Weight loss: -4.2 kg average
• hsCRP (inflammation marker): 1.56 vs 2.0 mg/L in placebo group

Kidney outcomes were disappointing. Major kidney disease events occurred in 8.4% vs 9.0% in the placebo group - no significant benefit. This contrasts with injectable semaglutide's FLOW trial, which showed a 24% reduction in major kidney events. The lower bioavailability of the oral formulation (around 1% of an equivalent injectable dose reaches circulation) may explain this difference.

The side effect trade-offs

GI side effects were significantly more common on oral semaglutide: 6.4% experienced adverse GI events serious enough to require treatment discontinuation, versus 2.0% in placebo. This is the practical barrier for oral semaglutide adoption - for a drug taken daily over years, a 6.4% discontinuation rate due to nausea and vomiting is clinically significant.

One finding deserves attention: neoplasms (new tumours) were more frequent in the semaglutide group - 6.8% versus 5.7% in placebo. The authors did not draw a causal conclusion, and the absolute difference is small, but it is a signal that regulators and prescribers will continue to monitor in the SOUL extension data.

Gallbladder disease was also elevated: 2.8% versus 2.2%. This is consistent with what other GLP-1 medications have shown across large trials - slowed gallbladder emptying is a class effect, not unique to any single drug.

What this means if you take oral semaglutide

If you use Rybelsus for type 2 diabetes, SOUL confirms you are getting real cardiovascular protection - specifically against heart attacks - even from the oral pill. That is reassuring. The injectable formulations still appear to offer broader protection (stronger kidney benefits, greater weight loss), but oral semaglutide is not just a convenience option with diluted benefits.

For people on injectable semaglutide (Ozempic or Wegovy), this data reinforces what the SELECT trial already showed: semaglutide protects the heart across its formulations.

One limitation worth naming: the SOUL population was nearly 70% white, with only 2.6% Black participants despite US and South African enrollment. The cardiovascular risk and drug response profiles of under-represented groups remain under-studied in this class of medication.

The nutrient gap angle

Long-term semaglutide use - whether oral or injectable - suppresses appetite, reducing food intake and therefore micronutrient intake. A four-year trial like SOUL underscores how long most patients stay on these medications. Over that time, cumulative deficiencies in vitamin B12, magnesium, iron, and vitamin D become increasingly relevant. B12 deficiency in particular is linked to elevated homocysteine, itself an independent cardiovascular risk factor - a potential irony for heart-protection-focused GLP-1 users who are not monitoring their nutrient status. GLP-1 Shield is formulated to fill these specific gaps during long-term GLP-1 use.

Frequently asked questions

Does oral semaglutide (Rybelsus) protect the heart the same way as injectable Ozempic?

The SOUL trial confirms oral semaglutide reduces major cardiovascular events by 14% in high-risk type 2 diabetes patients, driven by a 26% reduction in heart attacks. However, injectable semaglutide shows broader benefits including kidney protection and a stronger overall mortality effect. The oral pill works but appears less potent than the injectable formulation in some areas.

Who qualifies for the cardiovascular benefits of oral semaglutide?

The SOUL trial enrolled adults aged 50 and over with type 2 diabetes plus established cardiovascular disease, cerebrovascular disease, peripheral arterial disease, or chronic kidney disease. The cardiovascular benefit in SOUL applies specifically to this high-risk group - results cannot be directly extrapolated to people using semaglutide for weight loss without diabetes or without cardiovascular disease.

What GI side effects should I expect from oral semaglutide?

Nausea, vomiting, and diarrhea are the most common GI side effects. In the SOUL trial, 6.4% of participants discontinued due to GI adverse events, compared to 2.0% in the placebo group. Taking Rybelsus on an empty stomach with a small amount of water and waiting at least 30 minutes before eating - as directed - minimises but does not eliminate GI effects.

Does GLP-1 use increase cancer risk?

In the SOUL trial, neoplasms occurred in 6.8% of the semaglutide group versus 5.7% in placebo over four years. The absolute difference is small and no causal link has been established. Regulators continue to monitor this signal across all GLP-1 trials. No GLP-1 medication carries a cancer warning beyond the FDA black-box warning for rare medullary thyroid carcinoma.