Semaglutide’s Cardioprotective Effects Extend Beyond Weight Loss, SELECT Trial Confirms
Key Takeaways:
- Semaglutide significantly reduced major adverse cardiovascular events (MACE) in adults with overweight or obesity and established cardiovascular disease, regardless of baseline body weight.
- Reductions in waist circumference contributed partly – but not fully – to the observed cardioprotective benefits, suggesting mechanisms beyond weight loss.
- Early divergence in cardiovascular outcomes between the semaglutide and placebo groups indicates that benefits emerge rapidly after treatment initiation.
Semaglutide’s impact on heart health goes beyond weight loss
A landmark study published in The Lancet has revealed that semaglutide, a Glucagon-Like Peptide 1 Receptor Agonist (GLP-1RA), offers cardiovascular protection in people with overweight and obesity that cannot be explained by weight loss alone. The findings come from the large-scale SELECT trial, which explored the drug’s effect on major adverse cardiovascular events (MACE) in individuals without diabetes but with established cardiovascular disease.
GLP-1 receptor agonists were originally developed for glycaemic control in type 2 diabetes but have since demonstrated additional benefits, including weight reduction and decreased cardiovascular risk. Obesity itself increases cardiovascular mortality and morbidity through metabolic, inflammatory, and haemodynamic pathways. However, simple measures such as body weight fail to differentiate between fat and lean mass or between subcutaneous and visceral fat – the latter being more strongly associated with cardiovascular disease.
Until now, the relationship between changes in adiposity induced by GLP-1RAs and subsequent cardiovascular outcomes has remained unclear.
About the SELECT trial
The SELECT trial was a randomised, double-blind, placebo-controlled, phase 3 study evaluating whether semaglutide, used alongside standard care, could reduce cardiovascular events in adults with overweight or obesity. The trial enrolled 17,604 participants aged 45 years or older with a body mass index (BMI) of at least 27 kg/m² and established cardiovascular disease (defined as a history of myocardial infarction, stroke, or symptomatic peripheral artery disease).
Participants were randomly assigned to receive either once-weekly semaglutide injections or a placebo, with a gradual 16-week dose escalation to a target of 2.4 mg from week 17 onwards. The primary endpoint was MACE – a composite measure including non-fatal myocardial infarction, non-fatal stroke, and cardiovascular death.
Researchers analysed both baseline measures of adiposity (including waist circumference and body weight) and treatment-induced changes over time. Associations between these factors and MACE were assessed using a Cox proportional hazards model, with additional analyses distinguishing early (week 20) and long-term (week 104) effects.
Key findings
The mean follow-up period was nearly 40 months, with participants exposed to semaglutide for an average of 33.3 months and placebo for 35.1 months. Across all baseline body habitus measures, semaglutide reduced MACE incidence compared with placebo.
Higher baseline BMI was associated with female sex, younger age, non-Asian nationality, higher blood pressure, prediabetes, and greater inflammatory burden. Within both study arms, individuals with lower baseline adiposity had a lower MACE risk. In the semaglutide group, MACE risk fell by approximately 4% for every 5 kg reduction in baseline weight, although this trend was not significant in the placebo group. For waist circumference, both groups showed a 4% lower risk per 5 cm smaller baseline measurement.
By week 20, the rate of first MACE events had already diverged between the groups (hazard ratio [HR] 0.58), demonstrating an early cardioprotective effect.
At this point, mean changes in body weight and waist circumference were −6.4% and −5.0 cm in the semaglutide group, compared with −0.8% and −1.1 cm in the placebo group. These early changes accounted for about 70% of the total reductions seen at week 104. Importantly, 11% of all MACE events occurred within the first 20 weeks of treatment.
In the semaglutide group, greater reductions in waist circumference were associated with a lower subsequent MACE risk (HR 0.91; 95% CI 0.84–0.98; p = 0.02), while weight loss alone was not linearly linked to reduced risk. Among placebo recipients, those who lost at least 5% of their weight experienced higher MACE incidence and all-cause mortality, possibly reflecting unintentional or illness-related weight loss.
At week 104, semaglutide recipients who achieved the greatest weight loss had the lowest MACE incidence, whereas placebo recipients with comparable weight loss had the highest.
Waist circumference emerged as a stronger predictor
Analyses indicated that waist circumference reduction was a partial mediator of semaglutide’s cardiovascular benefits. Accounting for early changes in waist circumference reduced the treatment hazard ratio from 0.80 to 0.86 – suggesting that about one-third (33%) of the cardioprotective effect could be attributed to reduced abdominal fat, while the remainder likely involves other physiological mechanisms.
Crucially, time-varying changes in overall weight did not mediate the observed cardiovascular outcomes, underscoring that semaglutide’s heart-protective properties extend beyond simple weight loss.
Implications and limitations
The authors concluded that semaglutide was superior to placebo in reducing cardiovascular risk across all baseline weight and waist circumference levels, and that its benefits became evident early in treatment. They emphasised that early body weight reductions did not independently explain these benefits.
They cautioned, however, that analyses performed after randomisation were exploratory and not causal. The predominantly White, male study population also limits generalisability to broader groups, including women and ethnically diverse populations.
Despite these caveats, the findings strengthen the evidence that semaglutide’s cardioprotective effects go beyond adiposity reduction, pointing to additional metabolic, vascular, or anti-inflammatory mechanisms.
The SELECT trial was funded by Novo Nordisk, and is registered under ClinicalTrials.gov identifier NCT03574597.
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Use of GLP-1 Drugs Soars Among People Undergoing Bariatric Surgery, Study Finds
Key Takeaways:
- The use of GLP-1 receptor agonists such as semaglutide and tirzepatide among bariatric surgery patients increased sixteenfold between 2020 and 2024.
- Both people with and without Type 2 diabetes are increasingly using these drugs, showing a shift toward combination approaches in obesity management.
- Researchers emphasise the importance of multidisciplinary care and call for evidence-based guidelines to optimise the use of GLP-1 drugs alongside surgery.
A rapid evolution in obesity care
New research has revealed a dramatic increase in the use of weight loss medications among people undergoing metabolic and bariatric surgery, signalling a major shift in the treatment of obesity and Type 2 diabetes.
The study will be presented at the American College of Surgeons (ACS) Clinical Congress 2025, held in Chicago from 4–7 October.
“There is no one-size-fits-all approach to treating obesity, metabolic syndrome, or diabetes and its related conditions,” said Dr Patrick J. Sweigert, senior author of the study and bariatric and foregut surgeon at The Ohio State University Wexner Medical Center in Columbus, Ohio. “We are entering a new world of multidisciplinary care pathways and a new frontier of weight management that is important for patients and surgeons to think about.”
About the study
The research team conducted a large cross-sectional study examining the use of glucagon-like peptide-1 receptor agonists (GLP-1RAs) – specifically semaglutide (marketed as Wegovy and Ozempic) and tirzepatide (marketed as Zepbound and Mounjaro) – among people undergoing metabolic and bariatric surgery.
Using data from the Epic Cosmos database, which aggregates over 300 million patient records from healthcare institutions across the United States, Dr Sweigert and colleagues analysed nearly 365,000 individuals who underwent primary metabolic and bariatric surgery between 2018 and 2024.
The study assessed prescription patterns for semaglutide and tirzepatide, two of the most widely prescribed GLP-1RAs, to understand how their use has evolved before surgery.
Key findings
Preliminary findings showed a striking rise in GLP-1 prescriptions in the year preceding surgery – from 1.8% in early 2020 to 29.4% by the end of 2024, representing a sixteenfold increase.
Importantly, the surge was seen among people both with and without Type 2 diabetes, demonstrating the expanding role of GLP-1 drugs in obesity treatment beyond diabetes management.
Among those without Type 2 diabetes, use of GLP-1 drugs before surgery increased elevenfold – from 2.1% in early 2022 to 23.2% by late 2024. For those with Type 2 diabetes, preoperative use quadrupled – from 11.3% to 45.2% over the same period.
The median age of participants was 43 years, with a median preoperative body mass index (BMI) of 46. Women accounted for 80% of the cohort, and 33% had a diagnosis of Type 2 diabetes.
Changing perceptions and treatment pathways
Lead author Dr Stefanie C. Rohde, a general surgery resident at The Ohio State University Wexner Medical Center, explained that the findings represent an evolution in how people view their treatment options for obesity.
“While patients previously believed they had to choose between GLP-1 receptor agonists and surgery, we are now seeing that people are using both,” said Dr Rohde. “We know that patients can use GLP-1s after bariatric surgery to amplify their weight loss. But all of this is still very new in terms of how to manage patients effectively.”
She added that real-world data such as that provided by the Epic Cosmos network could play a critical role in establishing evidence-based clinical guidelines for how and when to integrate GLP-1 therapies – whether before surgery, in combination with it, or during postoperative follow-up.
Limitations and next steps
The researchers acknowledged several limitations. As with many analyses of large health databases, there may be inaccuracies in medical record data. The study was also unable to confirm whether individuals filled or took their prescribed medications, which could affect the reliability of prescription data.
Despite these caveats, the authors believe the study offers valuable insights into emerging trends in combined pharmacological and surgical approaches to obesity care.
Study co-author Mahmoud Abdel-Rasoul, MS, MPH, contributed to the data analysis and interpretation.
Looking ahead
The rapid rise in GLP-1 use among bariatric surgery candidates reflects a broader transformation in obesity treatment – one increasingly characterised by personalised, multidisciplinary, and data-informed care.
As Dr Sweigert noted, “We are entering a new world of multidisciplinary care pathways.” The challenge now lies in defining the most effective, safe, and sustainable ways to integrate these groundbreaking medications into established surgical treatment frameworks.
CCH insight:
These findings from the ACS, showing GLP-1 drug use prior to bariatric surgery, follow on from another study showing that many patients use GLP-1 drugs after surgery, in order to prevent weight regain. This will hopefully help to shift the thinking around obesity treatment. There is still a common perception that patients with obesity have the option of medication or bariatric surgery, and that it is a ‘one-and-done’ treatment. However, we know that obesity is a complex, chronic, relapsing disease which requires a long-term, multi-disciplinary approach. So we need medications, we need surgery and we need behavioural support and other interventions, used together in various combinations, at different times, to provide the life-long care that obesity patients require.
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Bariatric Surgery Delivers Greater Long-Term Benefits Than GLP-1 Medicines Alone, Cleveland Clinic Study Finds
Key Takeaways:
- People with obesity and type 2 diabetes who underwent bariatric surgery lived longer and experienced fewer serious complications than those treated with GLP-1 receptor agonist medicines alone.
- Surgery was associated with a lower risk of death, cardiovascular disease, kidney disease, and diabetes-related eye damage over a 10-year period.
- Patients who had surgery lost more weight, achieved better blood sugar control, and relied less on medications for diabetes, blood pressure, and cholesterol.
Major Cleveland Clinic study compares treatments
A large-scale study conducted by Cleveland Clinic has shown that people living with obesity and type 2 diabetes who undergo bariatric (metabolic) surgery experience significantly better long-term outcomes compared with those treated only with GLP-1 receptor agonist (GLP-1RA) medicines.
The research, published in Nature Medicine, followed nearly 4,000 patients and found that surgery was linked to longer life expectancy, greater weight loss, improved blood sugar control, and reduced reliance on diabetes and cardiovascular medicines.
“Even with today’s best medicines, metabolic surgery offers unique and lasting benefits for people with obesity and diabetes,” said Ali Aminian, M.D., Director of Cleveland Clinic’s Bariatric & Metabolic Institute and primary investigator of the study. “The benefits we observed went beyond weight loss. Surgery was linked to fewer heart problems, less kidney disease and even lower rates of diabetes-related eye damage.”
Study design and findings
The M6 study (Macrovascular and Microvascular Morbidity and Mortality after Metabolic Surgery versus Medicines) included 3,932 adults with both diabetes and obesity who received care at Cleveland Clinic over a period of up to 10 years.
- 1,657 participants underwent metabolic surgery, including gastric bypass or sleeve gastrectomy.
- 2,275 participants were treated with GLP-1 medicines such as liraglutide, dulaglutide, exenatide, semaglutide, and tirzepatide.
The median follow-up was 5.9 years (interquartile range 4.4–7.6 years).
Key outcomes:
At the 10-year mark, patients who underwent metabolic surgery had significantly better outcomes:
- 32% lower risk of death
- 35% lower risk of major adverse cardiovascular events (MACE), including heart attack, heart failure, or stroke
- 47% lower risk of chronic kidney disease (CKD)
- 54% lower risk of diabetes-related retinopathy (eye damage)
The 10-year cumulative incidence of all-cause mortality was 9.0% (95% CI 6.8–10.8%) in the metabolic surgery group, compared with 12.4% (95% CI 9.9–15.2%) in the GLP-1RA group (adjusted hazard ratio 0.68, 95% CI 0.48–0.96; P = 0.028).
The 10-year cumulative incidence of MACE was 23.7% (95% CI 20.0–27.6%) in the metabolic surgery group and 34.0% (95% CI 28.1–44.2%) in the GLP-1RA group (adjusted hazard ratio 0.65, 95% CI 0.51–0.82; P < 0.001).
On average:
- People who had surgery lost 21.6% of their body weight over 10 years.
- People treated with GLP-1 medicines lost 6.8% of their body weight.
- Haemoglobin A1c (HbA1c), a key marker of average blood sugar, improved by -0.86% with surgery compared with -0.23% with GLP-1 medicines.
In addition, surgery patients required fewer prescriptions for diabetes, blood pressure, and cholesterol management.
Expert perspectives
The findings underscore the long-term advantages of bariatric surgery even in the current era of advanced GLP-1 treatments.
“Even in the era of these powerful new drugs to treat obesity and diabetes, metabolic surgery may provide additional benefits, including a survival advantage,” said Steven Nissen, M.D., Chief Academic Officer of the Heart, Vascular & Thoracic Institute at Cleveland Clinic and senior author of the study.
Dr Aminian emphasised the importance of maintaining surgery as a treatment option:
“Our findings indicate that surgery should remain an important treatment option for obesity and diabetes. These long-term benefits are harder to achieve with GLP-1 medicines alone, as many patients stop using the medications over time.”
Study limitations and future research
The authors highlighted that the study was observational, not a randomised controlled trial. This means that while strong associations were observed, direct comparisons may be influenced by unmeasured factors.
In addition, the study did not focus exclusively on the most recent and highly effective GLP-1 medicines. The authors noted that future trials should directly compare metabolic surgery with newer GLP-1 therapies, such as semaglutide and tirzepatide, to help guide clinical decision-making.
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Higher Dose of Semaglutide Delivers Greater Weight Loss and Metabolic Improvements
Key Takeaways:
- Tripling the standard dose of semaglutide led to significantly greater weight loss and improved metabolic outcomes, without an increase in serious adverse effects.
- Participants on the higher dose achieved clinically meaningful reductions in body weight, waist circumference, and HbA1C levels, with nearly one-third losing 25% or more of their starting weight.
- Side effects were mostly mild and transient, suggesting that the higher dose may be a safe option for people requiring more intensive obesity treatment.
Landmark findings from the STEP UP trials
Tripling the standard dose of semaglutide – a widely prescribed glucagon-like peptide-1 receptor agonist (GLP-1RA) – resulted in markedly greater weight loss and cardiometabolic benefits, according to results from two large multicentre clinical trials led by UT Southwestern Medical Center. The studies, published in The Lancet Diabetes & Endocrinology, indicate that patients may be able to safely take a higher semaglutide dose than currently approved if they need to lose additional weight.
“Semaglutide and other drugs in its class have been life-changing for people living with obesity around the world. Our new findings suggest that increasing the dose can lead to even greater benefits and may be appropriate for some patients,” said study leader Dr Ildiko Lingvay, Professor of Internal Medicine in the Division of Endocrinology and in the Peter O’Donnell Jr. School of Public Health at UT Southwestern.
Context: The global obesity challenge
Obesity affects nearly one billion people worldwide, according to the World Health Organization, and is a major driver of conditions such as Type 2 diabetes, cardiovascular disease, certain cancers, and liver disease. GLP-1RAs, first authorised in the early 2000s, have transformed the management of Type 2 diabetes and, more recently, chronic weight management and cardiovascular risk reduction.
Semaglutide received approval from the US Food and Drug Administration (FDA) in 2017 for people with Type 2 diabetes and has since been approved at a 2.4 mg weekly dose for weight management in both the United States and European Union. While this dose can produce significant weight loss, many patients do not achieve their treatment goals.
The STEP UP trials: Design and participants
To explore whether higher doses could deliver additional benefits, researchers conducted two phase 3b clinical trials – STEP UP Diabetes and STEP UP Obesity – to compare the effects of a weekly 7.2 mg dose of semaglutide with the standard 2.4 mg dose and placebo.
In the STEP UP Diabetes trial, 512 adults with both obesity and Type 2 diabetes were randomly assigned to three groups:
- 307 participants received 7.2 mg semaglutide weekly.
- 103 participants received 2.4 mg semaglutide weekly.
- 102 participants received placebo.
Participants were followed for 72 weeks at 68 trial sites across eight countries in Europe, southern Africa, and North America, including UT Southwestern. All participants received counselling every four weeks to encourage reduced-calorie diets and increased physical activity.
Results: Substantial weight loss and metabolic gains
Weight loss outcomes
As seen in earlier studies, the standard 2.4 mg dose produced a mean weight loss of 10.4% of starting weight, compared with 3.9% in the placebo group. However, participants taking the higher 7.2 mg dose achieved an even greater mean weight loss of 13.2%.
In addition, those receiving 7.2 mg were significantly more likely to:
- Reach a 20% reduction in waist circumference – a key measure of cardiometabolic health.
- Achieve superior improvements in HbA1C, an indicator of blood sugar control.
Outcomes in people without type 2 diabetes
The STEP UP Obesity trial, which focused on people with obesity but without Type 2 diabetes, showed even more striking results. Nearly one-third of participants on the higher dose lost 25% or more of their starting weight, compared with 15% of those on the standard dose and none on placebo.
Safety profile and side effects
The most frequently reported side effects were gastrointestinal symptoms, such as nausea, diarrhoea, and constipation. These affected approximately half of participants taking semaglutide and about a quarter of those on placebo. Most symptoms occurred during the dose-escalation period and tended to diminish over time.
The only side effect reported more frequently in the higher dose group was dysaesthesia (a change in touch sensation), experienced by approximately 20% of participants taking 7.2 mg, compared with 5% of those on the lower dose. Importantly, there was no increase in serious adverse events associated with the higher dose.
“These findings reinforce the promise of semaglutide and other GLP-1RAs, with benefits that appear to increase at higher doses without compromising patient safety,” Dr Lingvay concluded.
Funding and disclosures
Both STEP UP trials were funded by Novo Nordisk A/S, the manufacturer of semaglutide. Dr Lingvay reports receiving personal consulting fees from Novo Nordisk.
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