Section
Trials
24 pages in this section, most recently updated September 4, 2026. Each opens with a plain-English summary and cites its sources.
01 · Trials
FeaturedSURMOUNT-1: tirzepatide 5, 10 and 15 mg for obesity over 72 weeks
You'll get: SURMOUNT-1 is the main trial behind Zepbound and the source of the over 20 percent figure for tirzepatide.
The main tirzepatide weight trial. 2539 adults without diabetes, 72 weeks: 15 to 21 percent weight loss across three doses versus 3 percent on placebo.
Updated September 4, 202602 · Trials
SURMOUNT-2: tirzepatide for obesity in people with type 2 diabetes
You'll get: SURMOUNT-2 tested tirzepatide 10 and 15 mg in 938 adults with type 2 diabetes and a BMI of 27 or more.
938 adults with type 2 diabetes and BMI 27 or higher, 72 weeks. Tirzepatide 10 or 15 mg: about 13 to 15 percent weight loss versus 3 percent on placebo.
Updated September 4, 202603 · Trials
SURMOUNT-3: tirzepatide after a 12-week intensive lifestyle programme
You'll get: SURMOUNT-3 enrolled 579 adults without diabetes who had just lost 5 percent or more in a 12-week lifestyle program.
579 adults who had just lost 5 percent or more in a 12-week lifestyle program, then tirzepatide or placebo for 72 weeks. Further change -18.4 vs +2.5.
Updated September 4, 202604 · Trials
FeaturedSURMOUNT-4: what happens when tirzepatide is stopped
You'll get: SURMOUNT-4 took 670 adults who had been on tirzepatide for 36 weeks and had half of them switch to placebo.
After 36 weeks on tirzepatide, 670 adults kept it or switched to placebo for 52 weeks. Kept it: lost 5.5 percent more. Switched: regained 14 percent.
Updated September 4, 202605 · Trials
FeaturedSURMOUNT-5: tirzepatide against semaglutide, head to head
You'll get: SURMOUNT-5 is the first trial to test tirzepatide against semaglutide head to head in people with obesity and no diabetes.
First head-to-head in obesity without diabetes. 751 adults, highest tolerated dose of each, 72 weeks. Tirzepatide about 20 percent, semaglutide about 14.
Updated September 4, 202606 · Trials
SURMOUNT-OSA: tirzepatide for obstructive sleep apnea with obesity
You'll get: SURMOUNT-OSA tested tirzepatide in adults with obesity and moderate to severe sleep apnea, with and without a PAP machine.
Two 52-week trials in adults with obesity and sleep apnea, with and without PAP. Breathing events per hour fell 25 to 29 on tirzepatide vs 5 on placebo.
Updated September 4, 202607 · Trials
SURPASS-2: tirzepatide versus semaglutide 1 mg in type 2 diabetes
You'll get: SURPASS-2 was a diabetes trial: it compared tirzepatide with semaglutide 1 mg in 1879 people with type 2 diabetes over 40 weeks.
1879 people with type 2 diabetes, 40 weeks, three tirzepatide doses vs semaglutide 1 mg. Main measure was blood sugar (HbA1c), not weight; tirzepatide won.
Updated September 4, 202608 · Trials
FeaturedSTEP 1: semaglutide 2.4 mg for obesity over 68 weeks
You'll get: STEP 1 is the main trial behind Wegovy and where the 15 percent figure for semaglutide comes from.
The main semaglutide weight trial. 1961 adults without diabetes, 68 weeks: about 15 percent weight loss on semaglutide 2.4 mg versus 2 percent on placebo.
Updated September 4, 202609 · Trials
STEP 2: semaglutide 2.4 mg for weight management in type 2 diabetes
You'll get: STEP 2 tested semaglutide 2.4 mg in 1210 adults with type 2 diabetes and a BMI of 27 or more.
1210 adults with type 2 diabetes and BMI 27 or higher, 68 weeks. Semaglutide 2.4 mg: about 10 percent weight loss versus 3 percent on placebo.
Updated September 4, 202610 · Trials
STEP 3: semaglutide with intensive behavioural therapy
You'll get: STEP 3 gave 611 US adults without diabetes an 8-week low-calorie diet and 30 coaching visits, with or without semaglutide.
611 US adults, 68 weeks, all with a low-calorie diet and 30 coaching visits. Weight loss about 16 percent with semaglutide 2.4 mg vs 6 percent on placebo.
Updated September 4, 202611 · Trials
FeaturedSTEP 4: continuing versus stopping semaglutide after 20 weeks
You'll get: STEP 4 asked what happens when people who have lost weight on semaglutide keep taking it or switch to placebo.
803 adults lost about 11 percent on semaglutide, then kept it or switched to placebo for 48 weeks. Kept: lost 8 percent more. Switched: regained 7 percent.
Updated September 4, 202612 · Trials
STEP 5: two years of semaglutide 2.4 mg
You'll get: STEP 5 asked whether weight comes back while people keep taking semaglutide 2.4 mg for two years.
304 adults, semaglutide 2.4 mg or placebo for 104 weeks. Weight change -15.2 percent versus -2.6 percent, nearly identical to the 68-week STEP 1 result.
Updated September 4, 202613 · Trials
STEP 8: semaglutide 2.4 mg weekly versus liraglutide 3.0 mg daily
You'll get: STEP 8 put weekly semaglutide 2.4 mg against daily liraglutide 3.0 mg, sold as Saxenda, in 338 US adults without diabetes.
338 US adults without diabetes, 68 weeks. Weekly semaglutide 2.4 mg: about 16 percent weight loss. Daily liraglutide 3.0 mg: about 6 percent.
Updated September 4, 202614 · Trials
STEP-HFpEF: semaglutide in heart failure with preserved ejection fraction and obesity
You'll get: This trial tested semaglutide 2.4 mg in 529 people with obesity and a type of heart failure called HFpEF.
529 people with obesity and HFpEF heart failure, semaglutide 2.4 mg or placebo, 52 weeks. Symptoms up 16.6 vs 8.7 points; weight down 13.3 vs 2.6 percent.
Updated September 4, 202615 · Trials
FeaturedSELECT: semaglutide and cardiovascular events in obesity without diabetes
You'll get: SELECT followed 17,604 people with heart disease and a BMI of 27 or more, but no diabetes, for about three years.
17,604 people with heart disease and BMI 27 or more, no diabetes, about 3 years. Heart attack, stroke or heart death: 6.5 vs 8 percent, drug vs placebo.
Updated September 4, 202616 · Trials
FLOW: semaglutide 1.0 mg and kidney outcomes in type 2 diabetes with chronic kidney disease
You'll get: FLOW tested semaglutide 1.0 mg in 3533 people with type 2 diabetes and chronic kidney disease.
3533 people with type 2 diabetes and kidney disease, about 3.4 years. Serious kidney events were 24 percent less common on semaglutide 1.0 mg than placebo.
Updated September 4, 202617 · Trials
SUSTAIN-6: semaglutide and cardiovascular outcomes in type 2 diabetes
You'll get: SUSTAIN-6 was a safety trial of semaglutide 0.5 or 1.0 mg in 3297 people with type 2 diabetes and high heart risk.
The 2016 heart safety trial of semaglutide in 3297 people with type 2 diabetes, 104 weeks. Heart events 6.6 vs 8.9 percent, plus a diabetic eye signal.
Updated September 4, 202618 · Trials
PIONEER 6: oral semaglutide and cardiovascular outcomes in type 2 diabetes
You'll get: PIONEER 6 tested the semaglutide pill in 3183 people with type 2 diabetes and high heart risk.
3183 people with type 2 diabetes at high heart risk, about 16 months. Heart events 3.8 vs 4.8 percent: the pill was shown heart-safe, not proven better.
Updated September 4, 202619 · Trials
FeaturedRetatrutide phase 2: a triple GIP, GLP-1 and glucagon receptor agonist for obesity
You'll get: Retatrutide is a test drug that acts on three hormone signals, not two like tirzepatide, and is not approved anywhere.
338 adults with obesity, 48 weeks, four doses of unapproved retatrutide. Top dose: about 24 percent weight loss vs 2 percent on placebo. Phase 2 only.
Updated September 4, 202620 · Trials
TRANSCEND-T2D-1: retatrutide phase 3 monotherapy in early type 2 diabetes
You'll get: This is the first published phase 3 trial of retatrutide, a test drug that is not approved anywhere.
537 adults with early type 2 diabetes, 40 weeks, unapproved retatrutide vs placebo. Blood sugar (HbA1c) fell 1.7 to 1.9 vs 0.8; weight 12 to 15 vs 3.
Updated September 4, 202621 · Trials
FeaturedATTAIN-1: orforglipron, a once-daily oral small-molecule GLP-1, for obesity
You'll get: Orforglipron is a GLP-1 pill taken once a day, with no fasting rules like the semaglutide pill has.
3127 adults with obesity and no diabetes, 72 weeks. Orforglipron 6, 12 and 36 mg daily: -7.5, -8.4 and -11.2 percent versus -2.1 percent on placebo.
Updated September 4, 202622 · Trials
ATTAIN-2: oral orforglipron for obesity in people with type 2 diabetes
You'll get: This trial tested the orforglipron pill in 1613 adults with type 2 diabetes and a BMI of 27 or more.
1613 adults with type 2 diabetes and BMI 27 or higher, 72 weeks. Orforglipron pill 6, 12 or 36 mg: 5, 7 and 10 percent weight loss vs 2.5 on placebo.
Updated September 4, 202623 · Trials
FeaturedREDEFINE 1: CagriSema (cagrilintide plus semaglutide) for obesity
You'll get: CagriSema is one weekly shot that pairs semaglutide with cagrilintide, a drug that copies the hormone amylin.
3417 adults without diabetes, 68 weeks. CagriSema, an unapproved semaglutide combination shot: about 20 percent weight loss versus 3 percent on placebo.
Updated September 4, 202624 · Trials
REDEFINE 2: CagriSema for obesity in people with type 2 diabetes
You'll get: This trial tested CagriSema, a semaglutide combination shot, in 1206 adults with type 2 diabetes and a BMI of 27 or more.
1206 adults with type 2 diabetes, 68 weeks. CagriSema, an unapproved combination shot: about 14 percent weight loss versus 3 percent on placebo.
Updated September 4, 2026