Type 1 diabetes is characterised by progressive loss of pancreatic beta cells. Studies have shown that interleukin (IL)–17 is likely a mediator for this destruction. Whether inhibition of IL-17 could preserve beta cell function in people with new-onset type 1 diabetes is unknown.

In this phase 2, randomised, multicentre, placebo-controlled, double-blind trial conducted at 17 study sites in Sweden, 127 adults aged 18–45 years old with newly diagnosed type 1 diabetes will be enrolled. Participants will be randomised to receive either subcutaneous IL-17 inhibitor or placebo for 52 weeks, in addition to their conventional therapy. The primary endpoint will be change in residual insulin secretion measured by the area under the curve for C-peptide in response to 2-hour mixed meal tolerance test between baseline and week 52. Additionally, masked continuous glucose monitoring will be performed during 14 days at the run-in period, week 13, week 26 and week 52. Secondary endpoints will be change in time in glucose range (3.9–10 mmol/L), time in hypoglycaemia (

Approvals were obtained from the Swedish Ethical Review Authority (Dnr 2020–05098) and the Swedish Medical Products Agency (Dnr 5.1-2021-105808) before participant enrolment. Participants provide informed consent before inclusion. Results of this study will be submitted for publication in international peer-reviewed journals and key findings will be presented at international scientific conferences.

ClinicalTrials.gov, NCT04589325.