Response to Letter to the Editor: "Checkpoint Inhibitor-Associated Autoimmune Diabetes is Distinct From Type 1 Diabetes".

Response

We would like to thank Dr. Kotwal and Dr. Kudva for their interest in our paper and for their letter to the editor. In response to their comments, we acknowledge that the reviews published by Stamatouli et al (1) and Kotwal et al (2) both add to the literature in this area, in addition to a number of other reviews (3–5), which have all been published since our submission.

In response to the queries, all patients were followed by the oncologists for the duration of the treatment with immune checkpoint therapy, and thereafter indefinitely on a 3- to 6-month basis. We note that the authors’ review included those with worsening type 2 diabetes (T2DM), whereas we focused our cohort only on what we define as checkpoint inhibitor-associated diabetes mellitus (CIADM), where patients develop sudden new onset insulin-requiring diabetes associated with a low C-peptide. In our series, only 1 of the 10 subjects developed this after pre-existing T2DM. We did not review those who developed steroid-induced hyperglycaemia or worsening T2DM in the absence of ketosis, as these scenarios likely represent different entities, and we wished to study the purest cohort of this new CIADM entity. As this is a retrospective cohort, testing of autoantibodies is not possible on the stored serum but will be performed prospectively in future studies.

As discussed by the authors, we feel that CIADM is a novel representation of autoimmune diabetes and likely represents both a subgroup of “type 1-like” diabetes, as well as a novel entity, which is likely to have a different pathobiology yet to be determined.