Research Shows Benefits of Tirzepatide for Type 1 Diabetes and Obesity
A new study shows that long-term use of tirzepatide in people with type 1 diabetes and overweight or obesity resulted in significant weight loss as well as marked improvements in A1C, time in range, and risk factors for heart and kidney disease.
Though life-changing medications like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) are only approved right now for type 2 diabetes, a growing body of evidence shows the potential benefits for people living with type 1 diabetes as well.
Promising results from a new study on tirzepatide for people with type 1 diabetes were presented recently at the ATTD 2025 conference in Amsterdam. During the study, 84 adults with type 1 diabetes and overweight or obesity were given tirzepatide off-label. After 21 months, participants experienced 23% weight loss and sustained improvements in glucose management.
“We’ve shown previously in studies that weight loss with semaglutide is less than half this. It’s more than a two-fold increase in weight loss with tirzepatide,” said Dr. Satish Garg, a professor at the Barbara Davis Center for Diabetes and lead author on the study.
In addition to improvements in A1C (0.5%) and time in range, Garg described significant improvements in cardiovascular and renal biomarkers such as blood pressure, cholesterol, triglycerides, and eGFR (a marker of kidney function). He also noted that at the end of 21 months, participants saw roughly a 16-fold decrease in the amount of total daily insulin needed.
“Such a huge decrease in insulin doses puts people at risk of DKA and hypoglycemia but none of them were reported, at least in this cohort,” said Garg.
Compared to semaglutide studies where 30-40% of study participants discontinued due to side effects, Garg said the only reason people discontinued in the tirzepatide study was due to cost (they either could no longer afford the drug or their insurance stopped covering it). Garg explained that the possible theory for why people experienced fewer side effects with tirzepatide is because the dosing increases were very slow (over the course of 4-5 months) and most people stopped at the 10 mg dose rather than the maximum 15 mg dose.
Though not a clinical trial, this study is especially important as 67% of people with type 1 diabetes have overweight or obesity, yet no weight loss medications are currently approved for them. Both diabetes and obesity increase the risk for long-term complications; together, the risk is even higher.
“Whether it’s type 1 or type 2 diabetes, both groups have a higher risk of developing heart and kidney disease. If these drugs are known to prevent both of those complications, it makes sense to use these drugs irrespective of which type of diabetes you have,” Garg said.
Other small studies in people with type 1 diabetes found that GLP-1 medications improve A1C, time in range, and reduce body weight, but clinical trials are needed to confirm the long-term benefits in this population.
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