A new retrospective study has revealed promising results for the off-label use of tirzepatide in people with type 1 diabetes, showing significant improvements in weight management, insulin requirements, and glycemic control. The findings were presented by Simon Berry, MbChB, Clinical Research Fellow in Diabetes at University of Sheffield, at the 2025 American Diabetes Association Scientific Sessions in Chicago.
Study Results Show Multiple Benefits
The longitudinal, retrospective study demonstrated that tirzepatide use in type 1 diabetes patients led to substantial clinical improvements after just three months of treatment. Participants experienced a significant mean weight reduction of 6.7 kg (95% CI, 5.4-8.0 kg; P <.001; n = 36), addressing a key concern for many patients with type 1 diabetes and obesity.
Perhaps more importantly for diabetes management, patients were able to reduce their mean total daily insulin dose by 21.6 units (95% CI, 12.8-30.4; P <.001; n = 28). This reduction was primarily driven by decreases in bolus insulin doses, with a mean reduction of 14.4 units (95% CI, 6.6-22.2; P = .001; n=26).
Improved Glycemic Control Despite Lower Insulin Use
Despite the significant reduction in insulin requirements, participants actually achieved better glycemic control. Time in range (70-180 mg/dl) increased significantly from 54.9% to 60.8% (95% CI, 0.0-11.8; P = .048; n = 36), indicating that patients spent more time within their target glucose range.
Growing Off-Label Use in Clinical Practice
Berry noted the increasing trend of off-label GLP-1 receptor agonist use in type 1 diabetes patients with obesity. "In people with T1D and obesity, there's quite a lot of off label GLP-1 agonist use and tirzepatide, as a proportion of that, is increasing," he explained. "People found it really beneficial, but I would caution that it's retrospective data and randomized control trials are needed to confirm those benefits that we found."
Tirzepatide's Unique Mechanism
Unlike traditional GLP-1 receptor agonists, tirzepatide acts on both the glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 receptors. This dual action enhances insulin secretion in a glucose-dependent manner, potentially lowering the risk of hypoglycemia while also reducing food intake by acting on appetite centers in the brain.
Tirzepatide was originally approved by the FDA in May 2022 as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes. However, it is not currently indicated for individuals with type 1 diabetes and has not been formally studied in this population until now.
Need for Controlled Trials
While the retrospective data shows promise, researchers emphasize the need for rigorous randomized controlled trials to establish the safety and efficacy of tirzepatide in type 1 diabetes patients. The current findings provide a foundation for future research into this potential new treatment approach for people with type 1 diabetes and obesity.
