We report the case of a 30-year-old male with psoriatic arthritis treated with secukinumab (anti-IL-17A) who developed new-onset type 1 diabetes mellitus (T1DM). During follow-up, a consistent reduction in insulin requirements and glycemic variability was observed in the two weeks following each dose of secukinumab. This suggests a possible immunomodulatory effect of IL-17 inhibition on beta-cell function and glycemic control. To our knowledge, this is the first report describing clinical benefits of secukinumab in the early stages of T1DM, highlighting its potential as a therapeutic tool in modulating autoimmune processes involved in disease progression.