Available NEJM Studies on Semaglutide (Ozempic)
Multiple high-quality New England Journal of Medicine studies have established semaglutide's efficacy across cardiovascular outcomes, chronic kidney disease, obesity management, metabolic dysfunction-associated steatohepatitis (MASH), and osteoarthritis-related pain.
Cardiovascular Outcomes
The SUSTAIN-6 trial (3,297 patients with type 2 diabetes) demonstrated that once-weekly subcutaneous semaglutide (0.5 mg or 1.0 mg) reduced the primary composite outcome of cardiovascular death, nonfatal MI, or nonfatal stroke by 26% compared to placebo (6.6% vs. 8.9%; HR 0.74 [95% CI 0.58–0.95]; P < 0.001) over 2 years 1, 2, 3, 4. This cardiovascular benefit was achieved despite higher discontinuation rates due to gastrointestinal adverse events.
The PIONEER 6 trial evaluated oral semaglutide in 3,183 patients with type 2 diabetes and high cardiovascular risk, demonstrating noninferiority to placebo for the primary composite outcome over 15.9 months (HR 0.79 [95% CI 0.57–1.11]; P < 0.001 for noninferiority) 5. Notably, death from cardiovascular causes was reduced by 51% (HR 0.49; 95% CI 0.27 to 0.92), and all-cause mortality by 49% (HR 0.51; 95% CI 0.31 to 0.84) 5.
Chronic Kidney Disease
The FLOW trial (3,533 participants with type 2 diabetes and chronic kidney disease) showed semaglutide 1.0 mg weekly reduced major kidney disease events by 24% (HR 0.76; 95% CI 0.66 to 0.88; P = 0.0003) after a median 3.4-year follow-up 6. The trial was stopped early for efficacy. Key findings included:
- Kidney-specific composite outcomes reduced by 21% (HR 0.79; 95% CI 0.66 to 0.94)
- Cardiovascular death reduced by 29% (HR 0.71; 95% CI 0.56 to 0.89)
- All-cause mortality reduced by 20% (HR 0.80; 95% CI 0.67 to 0.95)
- Mean annual eGFR slope improved by 1.16 ml/min/1.73 m² (P<0.001)
Obesity Management
The STEP 1 trial (1,961 adults with BMI ≥30 or ≥27 with weight-related comorbidities, without diabetes) demonstrated that semaglutide 2.4 mg weekly plus lifestyle intervention achieved -14.9% mean body weight reduction versus -2.4% with placebo at 68 weeks (treatment difference -12.4 percentage points; 95% CI -13.4 to -11.5; P<0.001) 7. Weight loss distribution was remarkable:
- 86.4% achieved ≥5% weight loss (vs. 31.5% placebo)
- 69.1% achieved ≥10% weight loss (vs. 12.0% placebo)
- 50.5% achieved ≥15% weight loss (vs. 4.9% placebo)
Cardiometabolic risk factors and physical functioning improved significantly. Gastrointestinal events were the primary reason for discontinuation (4.5% vs. 0.8% placebo) 7.
Metabolic Dysfunction-Associated Steatohepatitis (MASH)
A phase 3 trial (1,197 patients with biopsy-proven MASH and fibrosis stage 2 or 3) showed semaglutide 2.4 mg weekly achieved both primary endpoints at 72 weeks 8:
- Resolution of steatohepatitis without worsening fibrosis: 62.9% vs. 34.3% placebo (difference 28.7 percentage points; 95% CI 21.1 to 36.2; P<0.001)
- Reduction in liver fibrosis without worsening steatohepatitis: 36.8% vs. 22.4% placebo (difference 14.4 percentage points; 95% CI 7.5 to 21.3; P<0.001)
- Combined resolution and fibrosis reduction: 32.7% vs. 16.1% placebo (P<0.001)
Mean body weight decreased by -10.5% with semaglutide versus -2.0% with placebo 8.
Knee Osteoarthritis
The STEP 9 trial (407 participants with obesity [BMI ≥30] and moderate knee osteoarthritis) demonstrated that semaglutide 2.4 mg weekly reduced both body weight and pain over 68 weeks 9:
- Mean body weight change: -13.7% vs. -3.2% placebo (P<0.001)
- WOMAC pain score improvement: -41.7 points vs. -27.5 points placebo (P<0.001)
- SF-36 physical function score improvement: 12.0 points vs. 6.5 points placebo (P<0.001)
The pain reduction appeared to exceed what would be expected from weight loss alone, suggesting potential direct anti-inflammatory effects 9.
Key Clinical Considerations
Gastrointestinal adverse events (nausea, diarrhea, vomiting) are the most common side effects across all NEJM trials, typically transient and mild-to-moderate in severity 5, 7. These events are the primary reason for treatment discontinuation (4-7% of patients).
Long-term use is necessary for sustained benefit. Weight regain occurs after cessation, with mean weight regain of 11.6% of lost weight at 52 weeks post-treatment in STEP trials 10.
Oral formulation (PIONEER 6) offers comparable cardiovascular safety to subcutaneous administration, with similar efficacy profiles, providing an alternative for needle-averse patients 5, 11.