Glucagon-like peptide-1 (GLP-1) drugs became famous for shrinking waistlines, but their most consequential trials had nothing to do with appearance. Over the past three years, researchers tested these medicines on hard clinical outcomes in the heart, kidneys, liver, and airway, and the results have started to reclassify the class from weight-loss aids to broad cardiometabolic drugs. Here is what the evidence beyond weight loss actually shows.
The receptors these drugs hit are spread across the body
GLP-1 receptors are not confined to the pancreas and gut. They also appear in the brain, heart, blood vessels, and kidneys. That is why a drug designed to curb appetite can also change how those organs behave, and why trial after trial kept finding benefits the drugs were never built to produce. For the full account of how the class works and which agents are approved, see our main guide to GLP-1 drugs.
Semaglutide cut cardiovascular events by a fifth
The SELECT trial was the turning point. Among 17,604 adults with established cardiovascular disease and overweight or obesity but without diabetes, weekly semaglutide reduced the combined risk of cardiovascular death, heart attack, and stroke by 20% compared with placebo. It was the first time a weight-loss drug was shown to prevent cardiovascular events, and it established that treating obesity can count as cardiovascular prevention in its own right. Wegovy now carries a formal cardiovascular risk-reduction indication.
A kidney trial stopped early because the benefit was clear
The FLOW trial asked whether semaglutide could protect the kidneys in people with type 2 diabetes and chronic kidney disease. It was halted ahead of schedule after an interim analysis showed a 24% reduction in major kidney events and cardiovascular death. The drug also slowed the yearly decline in kidney function. That result places GLP-1 drugs alongside SGLT2 inhibitors as therapies that protect the kidney, not just the pancreas.
Tirzepatide became the first drug for sleep apnea
Not every result belongs to semaglutide. In the SURMOUNT-OSA program, tirzepatide reduced the severity of moderate-to-severe obstructive sleep apnea in adults with obesity by enough to earn the first drug approval for a condition long treated almost entirely with breathing devices and surgery. We covered the decision in our report on the tirzepatide sleep apnea approval.
Semaglutide cleared liver disease in most treated patients
The liver is the newest frontier. In the phase 3 ESSENCE trial, semaglutide resolved metabolic dysfunction-associated steatohepatitis (MASH), the aggressive, scarring form of fatty liver disease, without worsening fibrosis in 62.9% of patients, against 34.3% on placebo, at 72 weeks. The FDA is reviewing the drug for the condition. If approved, semaglutide would join resmetirom, the first dedicated MASH drug, which works through an unrelated mechanism. For the disease itself, see fatty liver is now the world’s most common liver disease.
It also helped a hard-to-treat form of heart failure
In the STEP-HFpEF trial, semaglutide improved symptoms and physical function in patients with obesity and heart failure with preserved ejection fraction, a common type of heart failure that has resisted most drug treatments. The benefit tracked with weight loss but appeared to reach beyond it.
The next questions are about addiction and the brain
The frontier keeps moving. Early studies suggest GLP-1 drugs may dampen cravings for alcohol, nicotine, and other substances, and researchers are testing whether the same brain effects could matter in Parkinson’s and Alzheimer’s disease. These signals are preliminary, drawn from small or early-stage work, and none has produced an approved use. They are worth watching, not banking on.
For the full landscape, including which drugs are approved and how they compare, start with our guide to GLP-1 drugs.
What the evidence cannot yet answer
Each of the individual trials cited above studied a population selected for high baseline risk of the outcome being measured: existing cardiovascular disease for SELECT, chronic kidney disease with reduced kidney function for FLOW, moderate-to-severe sleep apnea plus obesity for SURMOUNT-OSA, biopsy-confirmed MASH for ESSENCE. Whether the same magnitude of benefit extends to people at lower baseline risk, taking these drugs primarily for weight management, is inferred rather than directly demonstrated. Rebound weight gain after discontinuation is well documented, but the durability of the organ-specific benefits (heart, kidney, liver) after stopping treatment is not yet clear. Pancreatitis signals appeared in early observational data but a pooled analysis of 31 randomized trials totaling 40,274 patients (published in 2026) found no detectable increase in risk versus placebo; individual case reports continue and clinicians are watching. The thyroid C-cell tumor signal from rodent studies remains a class labeling concern, but no clear human signal has emerged in trial follow-up. Access and coverage vary widely by payer and indication, and the cost problem is structural rather than clinical.
References
- Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. Semaglutide and Cardiovascular Outcomes in Obesity Without Diabetes (SELECT). New England Journal of Medicine, 2023; 389: 2221-2232. DOI: 10.1056/NEJMoa2307563
- Perkovic V, Tuttle KR, Rossing P, et al. Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes (FLOW). New England Journal of Medicine, 2024; 391: 109-121. DOI: 10.1056/NEJMoa2403347
- Malhotra A, Grunstein RR, Fietze I, et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity (SURMOUNT-OSA). New England Journal of Medicine, 2024; 391: 1193-1205. DOI: 10.1056/NEJMoa2404881
- Sanyal AJ, Newsome PN, Kliers I, et al. Phase 3 Trial of Semaglutide in Metabolic Dysfunction-Associated Steatohepatitis (ESSENCE). New England Journal of Medicine, 2025; 392: 2089-2099. DOI: 10.1056/NEJMoa2413258
- Kosiborod MN, Abildstrom SZ, Borlaug BA, et al. Semaglutide in Patients with Heart Failure with Preserved Ejection Fraction and Obesity (STEP-HFpEF). New England Journal of Medicine, 2023; 389: 1069-1084. DOI: 10.1056/NEJMoa2306963