LEADER: Liraglutide Cuts Major Cardiovascular Events by 13 Percent in Type 2 Diabetes

The LEADER trial randomized 9,340 patients with type 2 diabetes at high cardiovascular risk and found that liraglutide reduced major adverse cardiovascular events by 13 percent over a median 3.8 years — the first cardiovascular outcome trial to show benefit for a GLP-1 receptor agonist.

Before 2016, every GLP-1 receptor agonist carried the same open question: these drugs lowered blood sugar, but regulators required proof they did not harm the cardiovascular system — and no trial had yet shown they helped it. The LEADER trial, published in the New England Journal of Medicine in 2016, changed that. It was the first cardiovascular outcomes trial to demonstrate that a GLP-1 receptor agonist not only is safe but actively reduces heart attacks, strokes, and cardiovascular death.

What the researchers did

An international team led by Steven Marso randomized 9,340 patients with type 2 diabetes at high cardiovascular risk across 410 sites in 32 countries. To qualify, participants had to be at least 50 years old with established cardiovascular disease — such as a prior heart attack, stroke, or vascular disease — or at least 60 with cardiovascular risk factors. About 81 percent entered with established cardiovascular disease.

Participants received liraglutide, escalated to a maximum of 1.8 mg injected once daily, or matching placebo, both on top of standard diabetes and cardiovascular care. The median follow-up was 3.8 years. The primary endpoint was the classic three-point MACE composite: death from cardiovascular causes, nonfatal heart attack, or nonfatal stroke.

What they found

The primary endpoint occurred in 13.0 percent of patients on liraglutide versus 14.9 percent on placebo — a hazard ratio of 0.87 (95 percent confidence interval 0.78 to 0.97), a 13 percent relative risk reduction that met both noninferiority and superiority.

The components told an interesting story. The largest driver was cardiovascular death, which fell by 22 percent (hazard ratio 0.78; 95 percent CI 0.66 to 0.93). Nonfatal heart attack and nonfatal stroke each trended in the favorable direction but did not reach statistical significance on their own. All-cause mortality — the endpoint least susceptible to classification debates — fell by 15 percent (hazard ratio 0.85; 95 percent CI 0.74 to 0.97).

Beyond the heart, LEADER reported a benefit on kidney outcomes: the composite of new-onset persistent macroalbuminuria, doubling of serum creatinine, need for dialysis, or renal death was significantly reduced with liraglutide, driven mainly by less new macroalbuminuria. Severe hypoglycemia was actually less frequent with liraglutide than placebo, while gastrointestinal side effects and gallbladder-related events were more common — consistent with the known class profile. Rates of pancreatitis and pancreatic cancer did not differ significantly between groups.

The investigators concluded that liraglutide, added to standard care, reduced the rate of major cardiovascular events in patients with type 2 diabetes at high risk, with lower rates of cardiovascular death and death from any cause.
Marso et al., N Engl J Med 2016 (LEADER)

Why it mattered

LEADER arrived months after the empagliflozin trial EMPA-REG OUTCOME had delivered the first positive cardiovascular result for any diabetes drug, and it established that cardioprotection was not limited to one drug class. It directly shaped guidelines: professional societies began recommending GLP-1 receptor agonists with proven cardiovascular benefit for patients with type 2 diabetes and established cardiovascular disease, a recommendation that has only strengthened since. The trial also set the template — and the expectations — for the outcome studies that followed, including SUSTAIN-6 for semaglutide and, later, SELECT in patients with obesity but without diabetes.

Limitations

LEADER enrolled a specific population: people with type 2 diabetes at high cardiovascular risk, the vast majority with preexisting disease. The results say little about primary prevention in lower-risk patients, and nothing directly about people without diabetes — the question SELECT later addressed for semaglutide.

The dose matters too. LEADER tested liraglutide up to 1.8 mg daily, the diabetes dose. It should not be read as evidence about the higher 3.0 mg dose used for weight management, nor can its effect size be transferred to other GLP-1 agents, which differ in potency and trial results. And like essentially all outcomes trials of its kind, LEADER was designed, funded, and analyzed by the manufacturer, Novo Nordisk — conducted under regulatory oversight with an independent endpoint committee, but still a fact readers should weigh when comparing it with future independent replications.

Finally, the absolute benefit was modest: over nearly four years, roughly two fewer MACE events per 100 patients treated. For an individual patient, that difference is meaningful but not dramatic, and it accrued on top of — not instead of — statins, blood-pressure control, and other standard care.