SURMOUNT Trials: Tirzepatide Dual Agonist Research Data

The SURMOUNT Clinical Program

The SURMOUNT trials evaluated once-weekly subcutaneous tirzepatide across populations including obesity without diabetes, type 2 diabetes, obesity with cardiovascular risk, and maintenance-phase treatment.

SURMOUNT-1: Obesity Without T2D

SURMOUNT-1 (N=2539) is the landmark obesity trial for tirzepatide.

Results at 72 weeks:

• Tirzepatide 5 mg: −15.0% body weight
• Tirzepatide 10 mg: −19.5% body weight
• Tirzepatide 15 mg: −20.9% body weight
• Placebo: −3.1%

At the 15 mg dose, 91% of participants achieved ≥5% weight loss, 57% achieved ≥20% weight loss.

SURMOUNT-2: Obesity with Type 2 Diabetes

SURMOUNT-2 (N=938) evaluated tirzepatide in obese adults with T2D:

• 15 mg dose: −15.7% body weight at 72 weeks
• HbA1c reduction: −2.1% with 15 mg
• 51% of participants achieved HbA1c <5.7% (normoglycemia)

SURMOUNT-3: Lifestyle Intervention Followed by Tirzepatide

Participants first underwent intensive lifestyle intervention (12 weeks), then were randomized to tirzepatide or placebo:

• Mean weight loss of 15.4% during lead-in
• Additional 18.4% reduction with tirzepatide after lead-in
• Total mean weight reduction from baseline: 26.6%

SURMOUNT-4: Weight Loss Maintenance

SURMOUNT-4 assessed what happens when tirzepatide is withdrawn after 36 weeks of treatment:

• Continued tirzepatide (72 weeks total): additional 5.5% loss
• Switched to placebo: regained 14.8% body weight

Dual Agonist Mechanism

Tirzepatide's superior weight loss vs. GLP-1-only agonists is attributed to:

1. GIP receptor activation: GIP receptors on adipocytes promote lipolysis and may reduce GLP-1-associated nausea at receptor level
2. Synergistic GLP-1 + GIP signaling: Combined receptor activation produces supra-additive effects on insulin secretion
3. Central satiety enhancement: Dual incretin receptor expression in hypothalamic nuclei may amplify satiety signaling

Research Summary

The SURMOUNT data establishes tirzepatide as the most efficacious incretin-based compound in clinical research for weight management endpoints, with ~21% mean weight loss at maximum dose representing a new benchmark in the field.