CATEGORY: METABOLIC & BLOOD SUGAR
What happens if the very first medicine for type 2 diabetes attacks blood sugar and body weight at the same time? That was the question behind TRANSCEND-T2D-1, and the answer came back loud. Over 40 weeks, the experimental weekly shot retatrutide cut HbA1c, the standard three-month blood sugar average, by 1.9 percentage points at its top dose versus 0.8 on placebo, while body weight fell 15.3% versus 2.6%.1
One Injection, Three Hormone Signals
Retatrutide mimics three gut and metabolic hormones at once: GLP-1 and GIP, which semaglutide and tirzepatide already use, plus glucagon, which raises the body’s energy burn. It isn’t approved anywhere yet. This trial, run by its maker Eli Lilly, was the drug’s first phase 3 test in diabetes, enrolling 537 adults whose blood sugar was no longer controlled by diet and exercise. Most were early in the disease. Their average time since diagnosis was just 2.5 years, and 85% had never taken a diabetes medication. A random draw gave each person one of three doses or placebo, double-blinded.
Most Participants Ended Up Out of the Diabetic Range
By week 40, between 82% and 89% of people on the drug had an HbA1c below 7%, the common treatment goal. Between 35% and 40% got all the way under 5.7%, which is the normal, nondiabetic range. Fasting glucose dropped about 30 points more than placebo. Weight was still falling when the trial ended. Blood pressure and triglycerides improved too. Those numbers echo what the drug’s sibling trial found in people with longer-standing diabetes and obesity, where weight was the primary target.2 Dangerous low blood sugar was rare: three people across both middle and high doses, none severe.
The Caveats That Come With a Drug This New
Side effects looked familiar for this drug family. Nausea, diarrhea, and vomiting were common during dose increases, and 2% to 5% of participants stopped because of side effects, versus none on placebo. Two less familiar signals deserve attention: 4% reported unusual skin sensations such as tingling, and 2% had worsening of diabetic eye disease. Forty weeks also can’t say anything about heart attacks, kidney failure, or the other complications diabetes treatment ultimately exists to prevent. Lilly funded the study and helped analyze it, and longer trials, including head-to-head comparisons against semaglutide and tirzepatide, are underway.
Key Takeaways
- In adults early in type 2 diabetes, weekly retatrutide lowered HbA1c by roughly a full percentage point more than placebo and cut body weight by up to 15%, with a third or more reaching normal-range blood sugar.
- The drug is investigational, the trial lasted 40 weeks, and its funder helped run the analysis. Effects on long-term complications are unknown.
References
- Bajaj HS, Welch M, Shah P, et al. Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial. The Lancet. 2026;S0140-6736(26)00967-0. link
- Bellido V, le Roux CW, Ekinci EI, et al. Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial. The Lancet. 2026;S0140-6736(26)01861-1. link