If you wear a Miraculous Medal you should give thanks to Saint Catherine Labouré. It was in a set of visions from the Blessed Mother that Saint Labouré created the Miraculous Medal worn by millions of Catholics.
Catherine was a member of the Daughters of Charity of Saint Vincent de Paul and aside from her visions, she is known for her taking care of the elderly.
Miraculously her body has remained incorrupt. Her feast day is November 28th. She is the patron saint of the Miraculous Medal, the elderly and the sick.