Big news just came out of one of the world’s largest diabetes and obesity conferences, the American Diabetes Association (ADA) Scientific Sessions, held in June 2026. Scientists shared the results of major trials for a brand-new weekly injection called retatrutide.
Retatrutide is a new once-weekly injection being studied for people living with obesity, type 2 diabetes and related health problems.
You may already have heard of medicines such as semaglutide (wegovy) or tirzepatide (mounjaro). These work by copying gut hormones that help control appetite, fullness and blood sugar.
Retatrutide is slightly different because it works on three hormone pathways:
GLP-1 — helps reduce appetite, improves fullness and helps blood sugar control.
GIP — helps the body handle sugar and may support weight loss.
Glucagon — may help the body use more energy.
This is why retatrutide is sometimes called a “triple agonist”. That simply means it switches on three different hormone receptors.
Retatrutide is not currently a routine prescription medicine. It is still being studied in clinical trials. The results shared at the American Diabetes Association Scientific Sessions in 2026 are exciting, but this medicine still needs full regulatory review before it can be used routinely.
Two big Phase 3 retatrutide trials were presented at ADA:
– TRANSCEND-T2D-1 — looked at people with Type 2 Diabetes who were not on insulin and had a BMI of 23 or above. Around 537 people took part, all with an average HbA1c of 7.9% and average weight of about 97 kg. They were followed for 40 weeks (around 10 months).
– TRIUMPH-1 — looked at people with obesity (BMI of 30 or above, or 27+ with a related health condition). Over 2,300 people took part. This was a longer trial — 80 weeks (around 20 months) — with an optional extension out to 104 weeks (2 years). Within this trial, there were also smaller groups of people with knee osteoarthritis (OA) and obstructive sleep apnoea (OSA), to see if retatrutide helped those conditions too.
People were split randomly into four groups: a placebo (dummy injection with no medicine), or retatrutide at 4 mg, 9 mg, or 12 mg doses per week.
This is where things get really impressive.
In people with obesity (TRIUMPH-1): People taking 12 mg Retatrutide weekly lost an average of 28.3% of their body weight over 80 weeks. For someone starting at 112 kg (about 248 lbs), that’s roughly 32 kg (70 lbs) lost. The results kept improving the longer people stayed on the medicine. In the 2-year extension group, average weight loss reached 30%.
Even the lowest dose of Retatrutide (4 mg), which only needed one dose increase step, still produced an average weight loss of 19%, which is already much better than most other treatments currently available.
Here’s a breakdown of how many people hit different weight loss milestones at 80 weeks on the 12 mg dose:
– 97% lost at least 5% of their body weight.
– 93% lost at least 10%.
– 88% lost at least 15%.
– 76% lost at least 20%.
– 63% lost at least 25%.
– 45% lost at least 30%.
– 27% lost at least 35%.
To put that in perspective, losing 35% of body weight was essentially unheard of with any medicine before. More than 1 in 4 people on the 12 mg dose achieved that.
In terms of BMI targets, about 65% of participants on the 12 mg dose reached a BMI under 30 (no longer classified as obesity), and about 33%*reached a BMI under 25 (in the healthy weight range), starting from an average BMI of 40.
In people with Type 2 Diabetes (TRANSCEND-T2D-1): People in the 9 mg and 12 mg groups lost an average of around 15–17% of their body weight over 40 weeks — up to about 17 kg (37 lbs). Even the 4 mg group lost nearly 11.5% on average.
In the TRANSCEND-T2D-1 trial, retatrutide significantly improved blood sugar levels in all three dose groups, meeting all of its main and secondary goals.
HbA1c is the measure of your average blood sugar over the past 3 months; a lower number is better. The average starting HbA1c was 7.9% (63mmol/mol):
– The placebo group ended up around 7.2% (55mmol/mol)after 40 weeks
– The 4 mg group came down to 6.2% (44mmol/mol)
– The 9 mg and 12 mg groups reached 5.9–6.0% (41-42mmol/mol), which is near the normal range!
In fact, up to 85% of people on retatrutide reached an HbA1c of 6.5% or below (a key treatment target), and almost half reached below 5.7% (39mmol/mol), which is essentially normal blood sugar (called normoglycaemia). These numbers are dramatically better than what we see with current standard medicines.
Obstructive sleep apnoea, often shortened to OSA, is when breathing repeatedly stops or becomes very shallow during sleep. It can cause loud snoring, poor sleep, morning headaches and daytime tiredness. It can also increase blood pressure and heart risk.
In the TRIUMPH-1 sleep apnoea group, retatrutide reduced the apnoea-hypopnoea index, or AHI. This is the number of breathing pauses or shallow breathing episodes per hour of sleep.
At the start, the average AHI was about 59 events per hour, which is severe.
By week 80, retatrutide reduced AHI by up to around 36 events per hour. This was described as more than a 60% reduction.
That is clinically important. It suggests that major weight loss with retatrutide may improve sleep apnoea severity in some people. However, people with sleep apnoea should not stop CPAP or other treatment unless advised by their sleep specialist.
Knee osteoarthritis is a common condition where the knee joint becomes painful, stiff and less mobile. Weight can put extra pressure through the knees, and inflammation may also play a role.
In the TRIUMPH-1 knee osteoarthritis group, retatrutide improved knee pain scores.
The study used a pain questionnaire called the WOMAC pain score. At baseline, the average score was about 6 out of 10.
By week 80, people taking retatrutide had a fall in pain score of up to about 4.3 points, compared with about 2.2 points with placebo.
This was described as more than a 70% reduction in pain with retatrutide.
This does not mean retatrutide is a direct painkiller. The improvement may be because of weight loss, reduced pressure on the joints and changes in inflammation. But for patients with obesity and painful knees, this is an important finding.
Retatrutide also improved several markers linked to heart and metabolic health. In the obesity study, retatrutide improved:
-Systolic blood pressure, with reductions up to about 12 mmHg.
-Triglycerides, a type of blood fat, with reductions up to about 41%.
-LDL cholesterol, sometimes called “bad cholesterol”, with reductions around 20%.
-hsCRP, a marker of inflammation, with reductions over 60%.
-Blood sugar status in people with prediabetes, with more than 95% returning to normal blood sugar levels in the highest-dose group.
People on Retatrutide also reported major improvements in physical function (how easy it is to move and do daily activities) and psychosocial wellbeing (how weight affects your mood, self-esteem, and relationships), based on a standardised quality-of-life questionnaire.
These are encouraging findings because obesity is not just about body size. It is linked to many health risks, including type 2 diabetes, high blood pressure, fatty liver disease, sleep apnoea, joint pain and cardiovascular disease.
The most common side effects on Retatrutide were gut-related. This is similar to other incretin-based medicines.
In the obesity study, common side effects included nausea, diarrhoea, constipation, indigestion, fatigue and dizziness.
These side effects were more common at the higher doses with up to 42% of people taking Retatrutide affected by nausea and up to 34% affected by diarrhoea.
Some people also reported injection site reactions and unusual skin sensations, sometimes described as burning, tingling or sensitive skin.
Urinary tract infections (UTIs) were slightly more common with retatrutide than placebo (up to 8%), mostly in women
Low blood pressure symptoms were also reported more often in people taking retatrutide, especially in those already taking blood pressure medication. This is important because if someone loses a lot of weight, their blood pressure medicines may need review.
Stopping treatment because of side effects is an important safety measure.
In the obesity study, stopping treatment because of any adverse event happened in 4.1-11.3% of people on retatrutide, with people on higher doses more likely to stop treatment, compared to about 4% on placebo. In the type 2 diabetes study, stopping treatment because of any adverse event happened in 2–5% of people taking retatrutide.
No severe hypoglycaemia, meaning dangerously low blood sugar, was reported in the type 2 diabetes study. This is reassuring, although the study did not include people taking insulin.
These results are important because they show that future obesity treatments may do much more than help people lose weight.
Retatrutide may potentially help with major weight loss, better type 2 diabetes control, lower blood pressure, improved cholesterol and triglyceride levels, reduced inflammation, improved sleep apnoea, less knee osteoarthritis pain, and better physical function and quality of life.
However, there are still important cautions.
Retatrutide is still being studied. We need longer-term data, including heart, kidney and liver outcome studies. We also need to understand who benefits most, who is more likely to get side effects and how best to support people to maintain weight loss safely.
It is also important to remember that obesity is a long-term medical condition. Medication is not a quick fix. People need good clinical assessment, nutrition support, physical activity advice, monitoring for side effects and long-term planning.
Because retatrutide has had a lot of attention, some people may be tempted to buy it online or from unofficial sellers.
Please do not do this. Unlicensed injections may be fake, contaminated, the wrong strength or unsafe. They may not contain what they claim to contain. They also come without proper medical checks, monitoring or support.
If you are living with obesity or type 2 diabetes and want to discuss treatment options, speak to a qualified healthcare professional.
The ADA 2026 Retatrutide studies are some of the most exciting results we have seen in obesity and type 2 diabetes treatment.
The weight loss results were substantial. The diabetes results were impressive. The improvements in sleep apnoea, knee pain and cardiometabolic risk markers suggest that treating obesity well can improve health across the whole body.
But this is still a developing area. Retatrutide is not yet a routine treatment. For now, the safest and most effective approach is to use approved treatments through proper medical care, with ongoing support for nutrition, movement, muscle strength, sleep, mental health and long-term weight maintenance.