Efficacy and Safety of Tirzepatide Once Weekly Versus Placebo in Participants Who Are Either Obese or Overweight With Weight-Related Comorbidities (SURMOUNT-1)

What Was Tested

This registered phase 3 trial tested Tirzepatide.

Participants with prediabetes at randomization may continue in an additional long-term treatment period to assess progression to type 2 diabetes and longer-term weight outcomes.

It had four arms (groups): one (experimental), one (experimental), one (experimental) and Arm 4: Placebo once weekly + lifestyle intervention (experimental).

The registry classes the interventions as behavioral and drug.

More on the Plan

The main treatment period is 72 weeks.

Participants identified with prediabetes at randomization can continue study treatment for up to 176 weeks (plus follow-up), allowing evaluation of longer-term weight management and time to onset/progression to type 2 diabetes.

Safety is monitored throughout, including adverse events and laboratory testing.

Who Took Part

2539 planned participants were the target.

It was open to people of any sex aged from 18 years with no upper age limit.

Healthy volunteers were not accepted; participants needed the condition being studied.

Examples of who could join: BMI ≥30 kg/m², OR BMI ≥27 kg/m² with ≥1 weight-related comorbidity (e.g., hypertension, dyslipidemia, obstructive sleep apnea, cardiovascular disease). History of at least one unsuccessful dietary effort to lose weight (self-reported). Investigator judges participant capable and willing to self-inject (or have assistance), follow lifestyle advice, maintain a diary, and complete questionnaires. Age ≥18 years. Meets protocol contraception/pregnancy criteria (as applicable) and provides written informed consent.

The full record lists 5 inclusion and 14 exclusion criteria; among the exclusions: type 1 or type 2 diabetes, history of ketoacidosis/hyperosmolar state, or screening labs diagnostic of diabetes; prior/planned bariatric surgery; recent/ongoing endoscopic or device-based obesity therapies; history of chronic or acute pancreatitis.

How the Study Was Run

The set-up was randomized, parallel-group and double-blind.

Because people in this Tirzepatide study were split into groups at random, differences between the groups are less likely to reflect who happened to join each one.

The Tirzepatide group and the comparison group ran side by side rather than switching.

As a double-blind Tirzepatide study, the assignments were hidden from both participants and investigators until the end.

Those kept unaware of assignments: participant and investigator.

It started in 2026-02-02 with completion listed for 2027-02-14.

It ran at 1 site in China.

Its stated primary purpose is treatment.

What Was Measured

Primary outcome: Mean percent change in body weight from randomization (time frame: 72 Weeks).

It also tracked 2 secondary outcomes, for example Mean change in body weight and Changes in cardiometabolic measures in triglycerides.

What This Means in Plain Language

Put simply, this is a phase 3, randomized trial of Tirzepatide in 2539 people.

With 2539 participants it is a large trial for this field.

It is still recruiting; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the Tirzepatide compound page, all human trials.