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Study breakdown

Tirzepatide achieves remarkable 21.4% weight loss in type 1 diabetes patients used off-label

RPEP-136322025Snell-Bergeon, Janet K; Kaur, Gurleen; Renner, Drew; Akturk, Halis K; Beatson, Christie; Garg, Satish K
evidence
The takeaway

In 100 adults with T1D, off-label semaglutide produced 9.1% weight loss and tirzepatide produced 21.4% weight loss over 1 year, with both improving HbA1c, compared to no change in 50 matched controls.

21.4% weight loss in T1D

Tirzepatide achieved remarkable weight loss in type 1 diabetes patients—a population with no approved weight loss medications

What the researchers found

Semaglutide: -19.2 lbs (-9.1%), HbA1c -0.54% (p=0.0001). Tirzepatide: -49.4 lbs (-21.4%), HbA1c -0.68%. Controls: no significant changes. 100 T1D patients over 1 year.

Why it matters

Obesity in T1D is growing due to intensive insulin therapy and has no approved drug treatment. These off-label results—especially tirzepatide's 21.4% weight loss—are striking and justify formal clinical trials.

How the study worked

Retrospective chart review of 100 T1D adults (50 semaglutide, 50 tirzepatide) plus 50 frequency-matched controls at a specialty diabetes clinic over 1 year.

What this study cannot tell us

Retrospective, non-randomized. Off-label use. Small sample. Safety concerns (DKA risk in T1D) not comprehensively assessed. Selection bias likely.

How to read the evidence

Retrospective with matched controls. Largest off-label T1D dataset. Hypothesis-generating for formal trials.

When this study was published

Published in 2025.

The bigger picture

T1D has been largely excluded from the GLP-1 drug revolution. This study demonstrates these drugs can be safe and remarkably effective in T1D, potentially expanding indications to millions of patients.

Questions still open

  • Is there increased DKA risk with GLP-1 drugs in T1D?
  • Should tirzepatide be formally studied for T1D weight management?
  • Can insulin doses be safely reduced during GLP-1 therapy in T1D?

Common questions

Can people with type 1 diabetes take semaglutide or tirzepatide?
These drugs are not officially approved for T1D, but this study of 100 T1D patients using them off-label showed significant weight loss (9% with semaglutide, 21% with tirzepatide) and improved blood sugar control. However, risks specific to T1D (like diabetic ketoacidosis) need careful monitoring.
Why is weight loss important for type 1 diabetes?
Intensive insulin therapy—necessary for T1D—often causes weight gain, which worsens insulin resistance and cardiovascular risk. Achieving significant weight loss while maintaining blood sugar control addresses both problems simultaneously.

Read the original research

Effectiveness of Semaglutide and Tirzepatide in Overweight and Obese Adults with Type 1 Diabetes.

Diabetes technology & therapeutics, 27(1), 1-9

View on PubMed ↗Publisher’s paper ↗

Citation

Snell-Bergeon, Janet K; Kaur, Gurleen; Renner, Drew; Akturk, Halis K; Beatson, Christie; Garg, Satish K. (2025). Effectiveness of Semaglutide and Tirzepatide in Overweight and Obese Adults with Type 1 Diabetes.. Diabetes technology & therapeutics, 27(1), 1-9. https://doi.org/10.1089/dia.2024.0328