She was born on March 27, 1970 in Moquegua, Peru. Her parents, Rafael Díaz Dueñas and Carmen Cabello Oviedo, were both teachers. Her uncle, Antonio Cabello Oviedo, had served as Mayor of Moquegua from 1987 until 1990. She is related to the late Peruvian writer, Mercedes Cabello de Carbonera, on the maternal side of her family. Díaz initially studied medicine at the National University of Tucumán in Argentina, but left the school at the end of the academic year to pursue teaching instead. She returned to Peru, where she enrolled in elementary education at the Instituto pedagógico Mercedes Cabello. She later completed her master's degree in education from the Moquegua campus of Cesar Vallejo University. She developed her career through a variety of in-classroom and administrative positions at state schools in Moquegua Region, including the director of the Sacred Heart of Jesuselementary school in Moquegua until 2017. She left her position as head of Sacred Heart of Jesus school in 2017 when her husband was appointed Ambassador to Canada. She met Martín Vizcarra when she was still a student. The couple now have four children - three daughters and a son - Diana, Daniela, Diamela, and Martino. They also have one grandchild, Mateo, who was born in 2017. Vizcarra has publicly praised his wife's role in their personal and professional lives. On July 6, 2016, he posted "That teacher who is by my side and gives my strength to keep going. That teacher is my wife, Maribel" to social media on Teacher's Day. Díaz Cabello largely kept a low profile during the 2016 presidential campaign, when presidential candidatePedro Pablo Kuczynski chose Martín Vizcarra as his running mate for Vice President of Peru. In an interview with América Televisión, Díaz explained that although she would prefer to stay away from politics, she supported her husband and his political future, telling the network, "I never liked it very much, because politics is politics, right? But if he wanted it and he wanted to do it, I have to support him..."
On March 23, 2018, upon the resignation of Pedro Pablo Kuczynski and the appointment of her husband as President of Peru, she became the First Lady of Peru, succeeding Nancy Lange. She announced that she would again leave the classroom to assume her duty's as the country's new First Lady, which includes protocol events and the supervision of an official office with an annual budget of approximately 600 thousand sols.
