GLP-1 Receptor Agonists Beyond Diabetes: Cardiovascular and Renal Evidence

GLP-1 Agonist Cardiovascular Benefit: From Diabetes Drug to Cardiorenal Therapy

When the FDA mandated cardiovascular outcomes trials for diabetes drugs in 2008, nobody expected the GLP-1 receptor agonist program to rewrite cardiorenal medicine. The mandate was about safety — proving new diabetes drugs did not cause heart attacks. Instead, trial after trial showed these drugs prevent them. And then SELECT showed they do it in patients who do not even have diabetes. And then FLOW showed they protect kidneys well enough to stop the trial early.

If you are managing patients with overlapping metabolic and cardiovascular risk — and in primary care, that is most of your panel — this evidence base is no longer optional reading. Here is a trial-by-trial breakdown, with the effect sizes, confidence intervals, and limitations that matter for the prescribing decisions you are actually making.

The Cardiovascular Outcomes Trials: A Trial-by-Trial Review

LEADER (Liraglutide, 2016)

LEADER, published in The New England Journal of Medicine in 2016, enrolled 9,340 patients with type 2 diabetes and high cardiovascular risk. Liraglutide 1.8 mg daily reduced 3-point MACE — cardiovascular death, nonfatal MI, or nonfatal stroke — by 13% (HR 0.87, 95% CI 0.78-0.97, p = 0.01). Cardiovascular mortality dropped 22% (HR 0.78, 95% CI 0.66-0.93). All-cause mortality dropped 15% (HR 0.85, 95% CI 0.74-0.97).

The NNT to prevent one MACE event over 3.8 years: 66. For cardiovascular death specifically: 98. These are modest numbers. But apply them across the millions of patients with type 2 diabetes and established cardiovascular disease, and the population impact is substantial. LEADER was the first clear signal that GLP-1 agonists do more than lower glucose.

SUSTAIN-6 (Semaglutide Subcutaneous, 2016)

SUSTAIN-6, also in The New England Journal of Medicine in 2016, was designed as a non-inferiority trial. It blew past that bar and hit superiority. In 3,297 patients with type 2 diabetes and cardiovascular disease or risk factors, subcutaneous semaglutide reduced 3-point MACE by 26% (HR 0.74, 95% CI 0.58-0.95, p = 0.02). The stroke reduction drove much of the benefit: 39% fewer nonfatal strokes (HR 0.61, 95% CI 0.38-0.99). Nonfatal MI dropped 26% (HR 0.74, 95% CI 0.51-1.08), though that did not reach significance independently.

SUSTAIN-6 was smaller with shorter follow-up (2.1 years), and the wide confidence intervals show it. But the point estimates consistently favored semaglutide over liraglutide, raising the obvious question: is semaglutide a more potent cardiovascular agent? We still do not have a head-to-head trial to answer that definitively. The clinical implication: both agents reduce events, and the differences between them are smaller than the gap between either one and doing nothing.

SELECT (Semaglutide 2.4 mg in Non-Diabetic Cardiovascular Disease, 2023)

SELECT changed the entire conversation. Published in The New England Journal of Medicine in November 2023, it enrolled 17,604 patients with established cardiovascular disease and BMI 27 or higher — without diabetes. This was the critical design choice: SELECT tested semaglutide 2.4 mg weekly (the obesity-indication dose) in patients whose primary need was cardiovascular risk reduction, not glucose control.

The results left no room for hedging. Semaglutide reduced 3-point MACE by 20% (HR 0.80, 95% CI 0.72-0.90, p < 0.001). All-cause mortality dropped 19% (HR 0.81, 95% CI 0.71-0.93). Heart failure events — a prespecified secondary composite — dropped 18% (HR 0.82, 95% CI 0.71-0.96). Cardiovascular death showed a 15% reduction (HR 0.85, 95% CI 0.71-1.01, p = 0.07), falling just short of independent significance.

You would need to treat 50 patients for 39.8 months to prevent one MACE event. Subgroup analyses showed consistent benefit whether patients were above or below age 65, male or female, BMI above or below 33, eGFR above or below 60, with or without prior heart failure. Every interaction p-value was non-significant. The benefit was not confined to any single subgroup — it was broad and consistent.

But here is what makes SELECT truly important: it proved the cardiovascular benefit of GLP-1 receptor agonists has nothing to do with glucose lowering. These patients did not have diabetes. The mechanisms are likely direct anti-atherosclerotic effects — a 21% reduction in hs-CRP points to reduced arterial inflammation, along with reduced visceral adiposity and potentially direct effects on plaque stability. Preclinical data showing GLP-1 receptor expression on vascular endothelium and macrophages support this. For the clinician, the takeaway is concrete: semaglutide is now a cardiovascular drug that happens to also treat diabetes and obesity, not the other way around.

Renal Outcomes: The FLOW Trial and Kidney Protection Evidence

FLOW (Semaglutide in CKD, 2024)

FLOW, published in The New England Journal of Medicine in May 2024, was the first dedicated renal outcomes trial for a GLP-1 receptor agonist. It enrolled 3,533 patients with type 2 diabetes and CKD (eGFR 25-75 mL/min with UACR 100-5000 mg/g, or eGFR 25-50 with UACR 100-5000 mg/g). Semaglutide 1.0 mg weekly versus placebo.

The data safety monitoring board stopped the trial early for efficacy. Semaglutide reduced the primary composite endpoint — sustained eGFR decline of 50% or more, sustained eGFR below 15, dialysis initiation, kidney transplantation, or kidney-related or cardiovascular death — by 24% (HR 0.76, 95% CI 0.66-0.88, p = 0.0003). Every individual renal component moved in the right direction: sustained 50% eGFR decline down 26% (HR 0.74, 95% CI 0.61-0.89), kidney failure (eGFR below 15 or dialysis) down 26% (HR 0.74, 95% CI 0.55-1.00).

The number that will stick with your nephrology-minded patients: the annual rate of eGFR decline slowed by 1.16 mL/min/1.73m2/year with semaglutide versus placebo (1.16 vs 2.19 mL/min/year, difference 1.03, 95% CI 0.69-1.37). For a patient sitting in front of you with eGFR 40, that rate difference translates to roughly 4-5 additional years before reaching eGFR 15. That is 4-5 more years before the dialysis conversation. That changes lives.

The subgroup analyses by baseline eGFR told the most important story. In patients with eGFR below 45 (n=1,146), semaglutide still worked (HR 0.73, 95% CI 0.59-0.91). In those with eGFR 45-60 (n=1,434), HR was 0.78 (95% CI 0.61-1.00). The benefit was numerically largest in the sickest kidneys — the patients with the most to lose from progression.

Renal Signals from Cardiovascular Trials

Before FLOW, the renal data came from secondary endpoints in cardiovascular outcomes studies. LEADER showed liraglutide reduced a composite renal endpoint (new macroalbuminuria, doubling of creatinine, ESKD, or renal death) by 22% (HR 0.78, 95% CI 0.67-0.92), driven mainly by less new-onset macroalbuminuria. SUSTAIN-6 showed a similar pattern: 36% reduction in the composite renal outcome (HR 0.64, 95% CI 0.46-0.88), again largely albuminuria-driven.

The question hanging over all that data was whether albuminuria reductions would translate to hard renal endpoints — actual kidney failure, not just surrogate markers. FLOW answered that definitively: yes. GLP-1 agonists now stand alongside SGLT2 inhibitors as the second drug class with demonstrated renoprotection from a dedicated renal outcomes trial. Your patient with diabetic CKD now has two evidence-based options for slowing progression, and the data support using both.

FDA-Approved Indications vs. Off-Label Evidence for GLP-1 Agonists

The evidence has outrun the labels. That gap matters for the prescribing decisions you face today.

FDA-approved cardiovascular indication: As of early 2026, semaglutide 2.4 mg weekly (Wegovy) has an FDA-approved indication for cardiovascular risk reduction in adults with established CVD and either obesity (BMI 30+) or overweight (BMI 27+). That is SELECT. Liraglutide 1.8 mg (Victoza) has an indication for cardiovascular risk reduction in adults with type 2 diabetes and established CVD. That is LEADER.

FDA-approved renal indication: At the time of writing, semaglutide does not yet have an FDA-approved indication specifically for CKD progression. The FLOW data clearly support this use, and a supplemental application is anticipated, but the regulatory process lags behind what the evidence already tells us.

Off-label evidence with strong support:

• CKD progression in patients with type 2 diabetes. FLOW provides Level 1 evidence (stopped-early RCT) for semaglutide reducing hard renal endpoints. Many nephrologists are already prescribing GLP-1 agonists for cardiorenal protection in CKD patients with diabetes, even without a formal renal indication on the label. The evidence justifies this.
• Heart failure with preserved ejection fraction. SELECT showed an 18% reduction in heart failure events, and subgroup data from STEP-HFpEF (semaglutide in obese HFpEF patients) showed improvements in Kansas City Cardiomyopathy Questionnaire scores, 6-minute walk distance, and a 21% reduction in heart failure-related events. The evidence is growing but not yet sufficient for a dedicated HFpEF indication.
• Metabolic-associated steatotic liver disease (MASLD) and MASH. Semaglutide 2.4 mg achieved MASH resolution without worsening fibrosis in 59% of patients vs. 17% with placebo in a phase 2 trial published in The New England Journal of Medicine in 2021. Phase 3 hepatic outcomes data are pending. Gastroenterologists and hepatologists are increasingly prescribing GLP-1 agonists for MASH, often using the diabetes or obesity indication as the formal basis.

Comparing GLP-1 Agonists to SGLT2 Inhibitors for Cardiorenal Protection

If you manage patients with type 2 diabetes and CKD, you face this comparison every week. There are no head-to-head outcomes trials, but the data allow some useful observations:

• MACE reduction: GLP-1 agonists have stronger evidence for atherosclerotic event reduction, with effect sizes of 14-26% across trials. SGLT2 inhibitors have shown more modest MACE reductions, with EMPA-REG OUTCOME being the outlier (14% MACE reduction, 38% CV death reduction).
• Heart failure: SGLT2 inhibitors have more robust evidence for heart failure hospitalization reduction, particularly in HFrEF (DAPA-HF, EMPEROR-Reduced). GLP-1 agonists show a more modest heart failure signal, though SELECT and STEP-HFpEF are expanding this evidence base.
• Renal protection: Both drug classes now have dedicated renal outcomes trials. DAPA-CKD showed a 39% reduction in the primary renal composite (HR 0.61); FLOW showed a 24% reduction (HR 0.76). The point estimates favor SGLT2 inhibitors, but different trial populations and endpoint definitions make direct comparison imprecise. The honest answer: both work, and neither replaces the other.
• Combination therapy: The question that matters most for your next prescription: does adding a GLP-1 agonist to an SGLT2 inhibitor provide incremental cardiorenal benefit? Subgroup analyses from SELECT suggest the MACE benefit of semaglutide held in the 17% of patients taking a baseline SGLT2 inhibitor (interaction p = 0.61). That subgroup was not powered for definitive conclusions, but the signal is encouraging.

Practical Prescribing Considerations and Emerging Directions

The trial data are compelling. Getting the drug into your patient is where it gets complicated.

• Dose matters for cardiovascular indication. SELECT used semaglutide 2.4 mg (the obesity dose), not 1.0 mg (the diabetes dose). Whether the cardiovascular benefit at the lower dose is equivalent, proportional, or absent remains unknown. If you are prescribing for cardiovascular risk reduction in a non-diabetic patient, the evidence supports 2.4 mg specifically. Do not assume the diabetes dose covers the cardiovascular indication.
• Titration and GI tolerability. Nausea, vomiting, and diarrhea hit 20-30% of patients initiating GLP-1 agonists, and GI intolerance is the primary reason patients stop. Slow titration (4-week intervals between dose increases) reduces but does not eliminate this. In SELECT, 16.6% of semaglutide patients discontinued treatment vs. 8.2% on placebo. Warn patients up front, titrate slowly, and plan for it.
• Supply considerations. GLP-1 agonist supply shortages have been recurrent since 2022. When prescribing for cardiorenal indications, consider which formulations are available and whether dose flexibility is needed. Tirzepatide (a dual GIP/GLP-1 agonist) has cardiovascular outcomes data pending from the SURPASS-CVOT trial, which may provide an alternative if results are positive.
• Insurance and prior authorization. Coverage varies significantly by indication. A patient prescribed semaglutide for type 2 diabetes may have different coverage than the same patient prescribed the same molecule for cardiovascular risk reduction or obesity. Prior authorization adds 15-30 minutes of physician or staff time per prescription — a real barrier to adoption, as discussed in the bench-to-bedside gap. This is one of the places where the 17-year translational delay lives: not in the evidence, but in the paperwork.

Several ongoing trials will further clarify the role of GLP-1 agonists in cardiorenal medicine: SURPASS-CVOT (tirzepatide for cardiovascular outcomes), SOUL (oral semaglutide, which confirmed a 14% MACE reduction in late 2024), and STEP-HFpEF DM (semaglutide in obese HFpEF with diabetes). This evidence base is expanding faster than any single clinician can track — precisely the kind of rapidly evolving, multi-specialty evidence landscape where Ailva helps physicians synthesize what matters most for the specific patient in front of them.