The studies in plain order
Semaglutide research shows where the drug helped and where questions remain.
Start with heart results, then read what the studies found about weight, kidneys, liver health, and blood sugar.
What the studies set out to learn
What did the main studies try to learn? They asked whether semaglutide helped the heart, weight, blood sugar, or kidneys. They also studied how it copies GLP-1, a hormone the gut sends out after food. One study compared it with another weight medicine.
Heart findings come first because they concern the gravest harm. Each part names the people who enrolled and says what changed; a number in brackets points to the source paper.
Some heart studies counted heart-related death, heart attack, and stroke together. The account below says whether that combined harm occurred less often. You won't need to sort through the study's math.
What Semaglutide changed for the heart
SELECT was the largest heart study, with 17,604 adults who carried extra weight and had known heart trouble but no diabetes. A 2.4 mg weekly shot cut by 20% the combined total of heart-related deaths, heart attacks, and strokes. A placebo group received a look-alike shot without semaglutide [3]. The paper's 95% range shows how far that group result might reasonably move; the whole range favored semaglutide, so the finding was firm. A 2024 review found that starting blood sugar didn't explain the benefit [13].
SUSTAIN-6 came first and enrolled 3,297 people with type 2 diabetes whose doctors saw a high heart risk. The same grave heart problems were about a quarter less common. Its 95% range favored semaglutide, though the benefit could be small or large. Serious diabetic eye trouble was more common [2], and that 95% range favored more trouble while leaving the amount unsure.
PIONEER 6 compared the daily pill with a placebo; serious heart problems were no more common with the pill [8]. Another study covered a stiff form of heart failure tied to obesity. A 2.4 mg weekly shot eased symptoms, helped movement, and led to more weight loss [9]. The semaglutide heart failure page describes those patients.
Semaglutide weight loss
STEP 1 gives the clearest weight finding. With a 2.4 mg weekly shot, people lost 14.9% of their starting weight on average by week 68. The placebo average was a loss of 2.4%. The difference between the averages was 12.4 percent of starting weight [1]. Related papers also found smaller waists, lower blood pressure, and better blood fats and sugar [10].
Mice and rats help explain why weight fell. Animals given semaglutide ate less and picked other foods, yet their bodies used energy at the same rate [4]. That work points to smaller meals rather than faster burning.
The benefit can fade when the drug stops. People in a later study regained much of the weight they had lost [21]. The effects page puts that finding beside the common complaints.
What is Semaglutide, and why does it last
What is semaglutide made to do? It copies GLP-1, a hormone sent out by the gut after food. In simple terms, the drug is a small protein used as medicine. A 94% match means almost all its parts resemble GLP-1.
Small changes help this GLP-1 copy stay in blood longer. Scientists changed the protein part they call 8, so a body enzyme called DPP-4 cuts up the drug more slowly. Another change lets the medicine ride on a blood protein [17]. The lasting GLP-1 effect sends insulin when sugar rises, slows the stomach, and lowers hunger [5].
FLOW studied 3,533 people with type 2 diabetes and lasting kidney disease. Some received a 1.0 mg weekly shot, while others received a placebo. Researchers counted kidney failure, a large lasting drop on kidney tests, or death tied to kidney or heart disease. Those grave outcomes were 24% less common with semaglutide [6]. Its 95% range stayed fully on the side of benefit, making the group finding firm.
Semaglutide vs tirzepatide
SURMOUNT-5 followed 751 adults with obesity for 72 weeks. The tirzepatide group lost 20.2% of starting weight on average, while the semaglutide group lost 13.7%. That gap was 6.5 percent of starting weight. The study's math showed that chance was an unlikely cause [7]. For weight alone, semaglutide vs tirzepatide favored tirzepatide in this study.
The study didn't settle every heart question. Tirzepatide copies a pair of gut hormones that help control sugar and hunger. Semaglutide copies one, called GLP-1, which the gut releases after food. Semaglutide also has heart findings from SELECT [3] and SUSTAIN-6 [2]. More weight loss doesn't prove more heart help, so your doctor may weigh those aims differently.
What Semaglutide peptide means in these studies
The main semaglutide peptide findings come from people. Here, peptide means a small protein used as medicine. STEP measured weight [1]. SUSTAIN-6 and SELECT counted grave heart problems [2][3]. FLOW watched kidney health [6], while SURMOUNT-5 compared two weight drugs [7].
The close work on hunger used mice and rats [4]. The medicine entered brain areas that guide eating. Animal work may suggest why something happened. Still, it can't show that people have the same brain response. Studies in people tell us what changed for people.
Another study checked four familiar kinds of medicine. Metformin is a diabetes pill, warfarin thins blood, atorvastatin lowers cholesterol, and digoxin treats some heart problems. Semaglutide didn't change their blood levels enough to matter [12]. Daily pills of 25 mg and 50 mg brought down sugar readings and body weight more than the 14 mg pill [11]. Those were study amounts, not directions for your care.