One of the primary sources we have which sheds light on Diogo's reign is a document from 1550, an inquest that he ordered into a plot by his predecessor, Dom Pedro Nkanga a Mvemba to regain his throne.

The alleged plot was orchestrated from the church in which Dom Pedro sought sanctuary and involved, aside from the unseated king, a number of Kongolese lords who remained loyal to the former regent.

King Diogo was anxious to extend the Roman Catholic faith in Kongo, work already started by Afonso I during his reign and due to Portuguese influence.

Though Afonso had created a model for the Roman Catholic Church in Kongo, Diogo hoped to extend it throughout the rural areas and also into neighboring countries.

However, Afonso brought the situations under control by creating a supervised slave trade that escalated Kongo's ruling class to divide which started plots toward the royal family to receive succession.

[2] In response to his uncle seeking refuge with religious leaders, Diogo developed his own network of clerical support, which he would control for the majority of his reign.