Semaglutide Clinical Trials: STEP Trial Results Explained

The STEP Trials: Semaglutide for Weight Loss

The STEP (Semaglutide Treatment Effect in People with obesity) clinical trial program is the largest body of evidence supporting semaglutide 2.4 mg for chronic weight management. These trials directly led to the FDA approval of Wegovy on June 4, 2021.

STEP 1: The Landmark Trial

Published in the New England Journal of Medicine in 2021, STEP 1 enrolled 1,961 adults with obesity (BMI of 30 or higher) or overweight (BMI of 27 or higher) with at least one weight-related condition, but without type 2 diabetes.

**Key results over 68 weeks:**

*Source: Wilding JPH, et al. "Once-Weekly Semaglutide in Adults with Overweight or Obesity." NEJM 2021;384:989-1002.*

STEP 2: Patients with Type 2 Diabetes

STEP 2 focused specifically on adults with overweight or obesity who also had type 2 diabetes, enrolling 1,210 participants.

**Key results over 68 weeks:**

Weight loss tends to be more modest in people with type 2 diabetes, which is a well-documented pattern across obesity medications.

*Source: Davies M, et al. "Semaglutide 2.4 mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2)." The Lancet 2021;397:971-984.*

STEP 3: Combined with Behavioral Therapy

STEP 3 combined semaglutide with intensive behavioral therapy and an initial low-calorie diet phase, enrolling 611 participants.

**Key results over 68 weeks:**

This trial demonstrated that combining medication with structured behavioral support can enhance results.

*Source: Wadden TA, et al. "Effect of Subcutaneous Semaglutide vs Placebo as an Adjunct to Intensive Behavioral Therapy." JAMA 2021;325(14):1403-1413.*

STEP 5: Two-Year Durability Data

STEP 5 is particularly important because it followed 304 participants for a full 2 years (104 weeks), providing the longest-duration data from the program.

**Key results at 104 weeks:**

*Source: Garvey WT, et al. "Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial." Nature Medicine 2022;28:2083-2091.*

What This Means for Patients

The STEP trials established several important findings:

1. Semaglutide 2.4 mg produces clinically meaningful weight loss (approximately 15% of body weight)

2. The majority of patients (over 85%) achieve at least 5% weight loss

3. Benefits extend beyond weight -- improving blood pressure, blood sugar, and cholesterol

4. Weight loss is maintained over at least 2 years of continued treatment

These results led to Wegovy becoming one of the most significant advances in obesity treatment. However, individual results vary, and the medication works best when combined with lifestyle changes including diet and physical activity.

*All GLP-1 medications require a prescription from a licensed healthcare provider. Consult with a qualified medical professional to determine if semaglutide is appropriate for your individual situation.*