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Article History

Received: 17 December 2025

Accepted: 1 April 2026

First Online: 26 May 2026

Acknowledgements

: We are grateful to I. Willaing Tapager and B. Cleal (Steno Diabetes Center Copenhagen, Denmark) for hosting one of the international T1DE workshops under the umbrella of STENO Diabetes Copenhagen. We are very grateful to our colleagues who participated in the workshops feeding in the phenotype definitions of T1DE.

: The case vignette series the phenotype analysis is based on is shared in the . Source data for the case vignette development cannot be shared for confidentiality reasons. Biomedical and anthropometric data can be shared upon request (corresponding author) for the purposes of systematic reviews and meta-analyses.

: This work was conducted as part of the National Institute for Health Research (NIHR; CS-2017-17-023)-funded STEADY project (Safe management of people with Type 1 diabetes and EAting Disorders studY). NZ’s salary was part-funded by the NIHR via the NIHR Clinician Scientist Award to MS; JT and KI are part-funded by the NIHR Mental Health Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London. MS was funded through an NIHR Clinician Scientist Fellowship (CS-2017-17-023). AH’s and JB’s salaries were in part funded by the NIHR Clinician Scientist Award to MS. EK was funded through a KCH-KMRT JRC PhD student fellowship. The workshop laying the foundation to this work in 2022 was financially supported by the Danish Diabetes Association.

: The authors declare that there are no relationships or activities that might bias, or be perceived to bias, their work. PL owns stock in Novo Nordisk. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

: MS designed the analysis plan and protocol for this work, MS, DP and AH conducted the STEADY data collection and research interviews, and KI, MR, JB, DT and MS conducted the clinical assessments and data collections that formed the basis for the London-T1DE vignettes. NP and DP led on the case vignette series development. EK and NZ contributed to data collection, extraction and analyses. MS, DP and PL led on the phenotype analyses. JA and NZ critically reviewed the case vignette series. MR, JT, KI, PL, DT, AH, NZ, MS, DP and NP contributed to phenotype analyses. DP, NP and MS drafted the article, and all authors critically reviewed the article and approved the final version. MS and DP had full access to the datasets. MS is the guarantor of this work.