Research Evidence
The clinical evidence for liraglutide spans two major trial programs: SCALE for weight management and LEADER for cardiovascular outcomes.
SCALE Obesity and Prediabetes: The pivotal trial enrolled 3,731 adults with BMI of 30 or greater (or 27 or greater with comorbidities) without diabetes. Published in the New England Journal of Medicine in 2015 by Pi-Sunyer et al., it randomized participants 2:1 to liraglutide 3.0 mg or placebo, both with lifestyle counseling. Liraglutide produced a mean placebo-adjusted weight loss of 5.4 kg (approximately 5.4% additional weight reduction beyond placebo). More than 63% of liraglutide-treated patients lost at least 5% of body weight versus 27% with placebo. A 3-year extension showed that liraglutide reduced progression from prediabetes to type 2 diabetes by 79%.
SCALE Diabetes: In 846 patients with type 2 diabetes, liraglutide 3.0 mg achieved 6.0% weight loss versus 2.0% with placebo over 56 weeks, with 54.3% of patients achieving 5% or greater weight loss. HbA1c was also significantly reduced.
SCALE Maintenance: This trial demonstrated that liraglutide could sustain and extend weight loss initially achieved through caloric restriction. Participants who had already lost at least 5% of body weight on a low-calorie diet were randomized to liraglutide or placebo. Those on liraglutide lost an additional 6.2% versus 0.2% with placebo over 56 weeks.
SCALE IBT: When combined with intensive behavioral therapy, liraglutide 3.0 mg produced 7.5% mean weight loss versus 4.0% with behavioral therapy plus placebo.
LEADER Cardiovascular Outcomes Trial: The landmark cardiovascular outcome trial randomized 9,340 patients with type 2 diabetes and high cardiovascular risk to liraglutide (1.8 mg) or placebo over a median follow-up of 3.8 years. Published in the New England Journal of Medicine in 2016, LEADER demonstrated a 13% reduction in the primary composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke (HR 0.87; 95% CI, 0.78 to 0.97; P=0.01). Cardiovascular death was reduced by 22% (HR 0.78) and all-cause mortality by 15% (HR 0.85). LEADER also showed a significant reduction in renal outcomes, driven primarily by reduced new-onset macroalbuminuria. These results established liraglutide as one of the first diabetes medications to demonstrate a cardiovascular mortality benefit. Importantly, these cardiovascular benefits were demonstrated specifically in the LEADER population: patients with type 2 diabetes at high cardiovascular risk. They should not be generalized to all liraglutide users, such as non-diabetic patients using Saxenda for weight management, for whom cardiovascular outcome data of this nature have not been established.
STEP 8 Head-to-Head Comparison: The STEP 8 trial directly compared semaglutide 2.4 mg weekly to liraglutide 3.0 mg daily in adults without diabetes. At 68 weeks, semaglutide produced 15.8% weight loss versus 6.4% with liraglutide. A significantly greater proportion of semaglutide patients achieved 10% or greater (70.9% vs 25.6%) and 15% or greater (55.0% vs 12.0%) weight loss. While this trial demonstrated semaglutide's superiority, it also confirmed that liraglutide produces clinically meaningful weight loss that exceeds lifestyle changes alone.
Pediatric Trial: A randomized controlled trial published in the New England Journal of Medicine in 2020 by Kelly et al. demonstrated that liraglutide 3.0 mg significantly reduced BMI standard deviation score in adolescents aged 12 to 17 with obesity, leading to the expanded pediatric approval.