Mathias Brix Danielsen, MD, PhD, is an assistant professor and medical doctor in the final year of specialist training in geriatric medicine. His professional background spans clinical care, research, and guideline development. Dr Danielsen’s main research focus is hydration care for frail older adults, particularly the use of subcutaneous hydration as an alternative to intravenous treatment. This work began during a clinical encounter with an older patient in whom repeated failed intravenous catheter attempts highlighted the need for gentler, evidence-based alternatives. Dr Danielsen subsequently completed a PhD on subcutaneous hydration, including a systematic review, an assessor-blinded randomized trial, and a radioisotope study. His research has informed national guidelines and contributed to international networks focused on improving hydration care for vulnerable older patients.