Abstract Aims Despite the established efficacy of tirzepatide in randomised controlled trials, real‐world effectiveness data in Japanese patients remain limited. This study evaluated the real‐world effectiveness and safety of tirzepatide in Japanese patients with type 2 diabetes over 52 weeks. Materials and Methods This multi‐site retrospective cohort study analysed 203 Japanese patients with type 2 diabetes who initiated tirzepatide at three outpatient clinics between July 2023 and August 2024. The primary endpoint was HbA1c change at 52 weeks. Subgroup analyses were performed on 22 predefined patient characteristics. Results The mean baseline HbA1c was 7.7%, and the mean body mass index was 29.1 kg/m 2 . Most patients (82.3%) had prior antidiabetic therapy, including insulin (30.0%). The overall mean HbA1c reduction was −0.91% (95% confidence interval: −1.08 to −0.74, p < 0.001), with 61.2% achieving <60;7.0%. Incretin‐naive patients achieved greater reductions than GLP‐1 RA switchers (−1.19% vs. −0.65%, p = 0.005). The mean weight loss was −3.4 kg. The treatment persistence rate was 92.6%. Gastrointestinal adverse events occurred in 6.4% of patients, and no hypoglycaemia was documented. Conclusions Tirzepatide demonstrated clinically meaningful HbA1c reductions with favourable safety profiles in Japanese patients. The effectiveness was consistent across diverse subgroups, supporting its integration into diabetes management in Japan.
Minakata et al. (2026) studied this question.