TIRZEPATIDE, a dual GIP and GLP-1 receptor agonist already widely used in Type 2 diabetes and obesity management, is gaining interest for use in people with Type 1 diabetes (T1D) who also have obesity. Obesity in T1D can worsen insulin resistance and heighten cardiometabolic risk, emphasising the need for effective therapeutic options. A new real-world study from a UK tertiary centre sheds light on tirzepatide’s impact in this setting, revealing meaningful clinical outcomes. A key finding was a near 10% reduction in body weight after 6 months of treatment.
This longitudinal, retrospective study reviewed data from 57 patients with T1D who were initiated on tirzepatide. Researchers extracted information from case notes and continuous glucose monitoring (CGM) cloud platforms to assess weight, insulin use, glycaemic control, adverse events, and hospital admissions. Two-tailed paired t-tests were used to compare clinical metrics before and after 6 months of treatment. Pearson’s correlation was applied to explore associations between weight change and glycaemic improvement.
After 6 months of tirzepatide use, the mean weight loss was 9.8 kg (9.3%; p<0.001; n=42). Total daily insulin dose decreased significantly by 25.2%, from 74.4 to 57.3 units (p<0.001; n=27), with both basal and bolus doses showing substantial reductions. HbA1c dropped by an average of 3.7 mmol/mol (p=0.008; n=33). Notably, there was no significant correlation between the degree of weight loss and improvements in CGM-derived glycaemic metrics. Side effects were reported by 37% of participants, with nausea and abdominal pain being most common. Nonetheless, 88% remained on treatment at 6 months. Three individuals were hospitalised due to gastrointestinal symptoms, but there were no cases of pancreatitis.
This early real-world evidence suggests tirzepatide may offer substantial benefits in people with T1D and obesity, including significant weight loss, lower insulin requirements, and modest improvements in glycaemic control, without a rise in hypoglycaemia. However, limitations include the retrospective design, small sample size for some metrics, and lack of a control group. Further randomised controlled trials in T1D are essential to confirm safety and efficacy. For clinicians managing T1D in the context of obesity, these findings offer cautious optimism and support the considered use of tirzepatide under close supervision.
Reference
Berry SA et al. Tirzepatide as an adjunctive therapy in type 1 diabetes: real-world experience from a large UK centre. Abstract 825. EASD 2025. 15-19 September, 2025.
