Following the 6 December 1991 death of 108-year-old Niels Nielsen, Matthiesen became the oldest living person in Denmark. She was never the oldest Danish native due to former oldest man ever Christian Mortensen outliving her. Upon her death, the title passed to Olga Kofoed, then aged 107.
In August 1994, Matthiesen surpassed the final age of Louise A. Bramsen to become the oldest person ever to reside in Denmark. She would hold this record for almost 23 years, with her age not being surpassed by a resident of Denmark until Ellen Brandenborg did so in May 2017. In November 1994, she became Denmark’s first ever resident supercentenarian.
Matthiesen’s age was previously validated by the Gerontology Research Group (GRG), her age having been verified by Bernard Jeune. On 25 May 2024, LongeviQuest validated her age after verification by Jimmy Lindberg.