Efficacy and Safety of Tirzepatide in Overweight and Obese Adult Patients with Type 1 Diabetes

Introduction & Objective: Most patients with type 1 diabetes (T1D) in the USA are overweight (OW) or obese (OB), contributing to insulin resistance and suboptimal glucose control. The primary FDA approved treatment for T1D is insulin, which may adversely affect weight. Tirzepatide is approved for managing type 2 diabetes, improves glucose control, facilitates weight loss, and improves CVD outcomes. We assessed the use of tirzepatide in OW/OB subjects with T1D. Methods: This was a retrospective single-center, real-world study in 62 OW/OB adult patients with T1D who were prescribed tirzepatide (treated group) and followed for one year. At least 3 months of use of tirzepatide was one of the inclusion criteria. Based on the inclusion criteria this study represents 62 patients out of 184 prescribed tirzepatide. The control group included 37 OW/OB patients with T1D (computer frequency matched by age, duration of diabetes, gender, BMI and glucose control) who were not using any other weight-loss medications during the same period. The mean (±SD) dose of weekly tirzepatide at 3-months was 5.6±1.9 mg which increased to 9.7±3.3 mg at one-year. Results: The gender, mean baseline age, duration of diabetes, and HbA1c were similar in the two groups, while BMI and weight were higher in the treated group. There were significantly larger declines in BMI and weight in the treated group than controls across all time points among those in whom data was available. HbA1c decreased in the treated group as early as 3-months and was sustained through a one-year follow-up (-0.67% at one year). As expected, insulin dose decreased at 3 months and throughout the study period. There were no reported hospitalizations from severe hypoglycemia or DKA. The mean glucose, TIR, TAR, SD, and CV (CGM metrics) significantly improved in the treated group. Conclusions: In this pilot (off-label) study, we conclude that tirzepatide facilitated an average 18.5% weight loss (>46 pounds) and improved glucose control in OW/OB patients with T1D at one year. For safe use of tirzepatide in patients with T1D, we strongly recommend a large prospective randomized control trial in OW/OB patients with T1D.