#EASD2025: Real-world data suggest tirzepatide reduces insulin needs in type 1 diabetes

TouchENDOCRINOLOGY coverage from EASD 2025:

At the EASD 2025 congress (Vienna, Austria; 15–19 September), new research from the University of Sheffield explored the potential role of tirzepatide as an adjunctive therapy in people with type 1 diabetes and obesity. Tirzepatide, a dual GIP and GLP-1 receptor agonist currently licensed for type 2 diabetes and obesity, may offer benefits in weight reduction, insulin dose requirements, and glucose control without increasing hypoglycaemia risk. We spoke with Dr Simon Berry and Dr Ahmed Iqbal about their real-world study, its findings, and the implications for future clinical practice.

Q. Tirzepatide is already approved for type 2 diabetes and obesity. Could you explain its mechanism of action, and why your team thought it might be beneficial as an adjunct therapy in type 1 diabetes?

Dr Simon Berry:  Tirzepatide is a dual GIP and GLP-1 receptor agonist that mimics the actions of gut hormones. In people with type 2 diabetes, clinical studies have shown that it improves glycaemic control and promotes significant weight loss. Obesity is increasingly common in people living with type 1 diabetes, and it drives insulin resistance, thereby worsening cardiometabolic risk. We therefore hypothesized that in people with both obesity and type 1 diabetes, tirzepatide could help reduce weight, improve insulin sensitivity, and ultimately improve diabetes control.

Q. What were the main aims of the study and how did you assess safety, tolerability and efficacy in this type 1 diabetes population?

Dr Ahmed Iqbal: We set out to answer two key questions: first, is tirzepatide relatively safe in people with type 1 diabetes, and second, does it deliver the anticipated benefits in this population? We reviewed all patients with type 1 diabetes and obesity who were started on tirzepatide in our centre between March and October 2024. To assess efficacy, we looked at changes in weight, insulin requirements, HbA1c and continuous glucose monitoring metrics. To evaluate safety and tolerability, we monitored side effects, hospital admissions, and whether participants remained on the drug at six months of follow-up.

Q. Could you give us an overview of the main findings from this study, in terms of weight loss, insulin use and blood glucose control?

Dr Ahmed Iqbal:  The three main findings were clear. First, participants experienced a mean weight loss of around 10% at 6 months. Second, daily insulin requirements fell by about 25%, with reductions seen in both bolus (mealtime) and basal (background) insulin doses. Third, glucose control improved: time in range increased by around 7%, and time in the tighter target range also increased significantly, by more than 5%. Crucially, these improvements were achieved without any increase in hypoglycaemia. In short, patients gained metabolic benefits without additional safety concerns around low blood glucose.

Q. Some participants reported gastrointestinal side effects and a few required hospital admission. How should clinicians weigh these risks against the benefits, and what does this mean for potential broader use in type 1 diabetes?

Dr Ahmed Iqbal:  This is a key consideration. In our practice, we use tirzepatide off label on a case-by-case basis, and we are very clear with patients that it has not yet been tested in large randomized controlled trials in type 1 diabetes. We explain that the primary aim is not weight reduction per se, but improving insulin resistance, which is harmful in people with type 1 diabetes.

Most patients tolerate the medication well, but gastrointestinal side effects such as nausea, vomiting, abdominal discomfort and diarrhoea are common. These usually resolve over time. Rare but more serious risks include pancreatitis and gallstones, and we counsel patients carefully about these. Importantly, in our cohort, nearly 90% of patients were still taking tirzepatide at six months, which is encouraging. Looking ahead, the potential longer-term benefit lies in reducing cardiometabolic risk, particularly cardiovascular disease, but this must be confirmed in robust randomized controlled trials.

Q. Based on your results, how do you see tirzepatide fitting into the treatment paradigm if future randomized controlled trials confirm your findings?

Dr Simon Berry:  At this stage, we see tirzepatide primarily as a treatment for people with type 1 diabetes and obesity, where it could help address the excess cardiometabolic risk associated with insulin resistance. Previous studies of other GLP-1 agonists in type 1 diabetes did not show the same level of benefit, which makes these findings with tirzepatide particularly promising. Future studies should explore its effects across a wider range of BMI categories, age groups, sexes, and ethnicities to better understand who will benefit most. In particular, people diagnosed with type 1 diabetes at a young age may stand to gain from earlier introduction of therapies that mitigate cumulative cardiovascular risk.

Dr Ahmed Iqbal:  I would emphasize the importance of studying this approach in younger adults, aged 16–25 years. Cardiovascular risk begins to accrue early and progresses more rapidly in type 1 diabetes. If tirzepatide or similar agents can deliver long-term cardiometabolic benefits, starting treatment earlier could have major implications for reducing risk as these individuals age. We don’t yet have trial data to confirm this, but at least one study, funded by Breakthrough Type 1 Diabetes, is already underway, and our centre is actively contributing to this research.