A Study of Tirzepatide (LY3298176) Compared With Placebo in Adults With Type 1 Diabetes and Obesity or Overweight

What Was Tested

This registered phase 3 trial tested Tirzepatide.

Participation in the study will last about 49 weeks.

It had five arms (groups): one (experimental), one (experimental), one (experimental), one (experimental) and Placebo (placebo comparator).

Participants will receive tirzepatide subcutaneously (SC).

Participants will receive tirzepatide SC.

Participants will receive tirzepatide SC.

The registry classes the interventions as drug.

Who Took Part

Enrollment: 905 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: Have type 1 diabetes and on insulin treatment for at least one year prior to screening. Have a body mass index (BMI) of ≥25 kilograms per square meter (kg/m2) at screening. Are of stable weight for at least 90 days prior to screening and agree to not start an intensive diet or exercise program during the study.

The full record lists 4 inclusion and 5 exclusion criteria; among the exclusions: have experienced one or more events of severe hypoglycemia during the period of 90 days prior to screening and until randomization; are currently receiving or planning to receive treatment for diabetic retinopathy and/or macular edema; have had chronic or acute pancreatitis.

How the Study Was Run

It was run as a randomized, parallel-group and double-blind study.

Random assignment meant chance, not the researchers, decided who got Tirzepatide and who got the comparison, which limits bias.

Groups ran in parallel: each of the participants stayed in one arm throughout.

Neither the participants nor the staff measuring them knew who was on Tirzepatide, so expectations could not easily colour the readings.

Those kept unaware of assignments: participant and investigator.

It started in 2025-04-25 with completion listed for 2026-11.

It ran at 146 sites in United States (31), Japan (29), France (13), Argentina (12), Brazil (10) and Israel (10).

Its stated primary purpose is treatment.

What Was Measured

Primary outcome: Change from Baseline in Hemoglobin A1c (HbA1c) (time frame: Baseline, Week 40).

It also tracked 13 secondary outcomes, for example Change from Baseline in Body Weight, Percent Change from Baseline in Body Weight, Change from Baseline in Waist Circumference, Change from Baseline in Systolic Blood Pressure (SBP), Percent Change from Baseline in Fasting Triglycerides and Percent Change from Baseline in Fasting Non-High-Density Lipoprotein (non-HDL) Cholesterol.

What This Means in Plain Language

Put simply, this is a phase 3, randomized trial of Tirzepatide in 905 people.

With 905 participants it is a large trial for this field.

Its status is active not recruiting; no results are posted to the registry yet, so nothing here describes outcomes.

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