Hi, Diane —

Diane is derived from Diana:

• Blessed Diana, Feast Day June 9 from Catholic.org
  
  
• Blessed Diana, Feast Day June 9 from Saints.SQPN
  Notes about your extended family in Heaven.
  

The Catechism states:

2156 The sacrament of Baptism is conferred "in the name of the Father and of the Son and of the Holy Spirit." In Baptism, the Lord's name sanctifies man, and the Christian receives his name in the Church. This can be the name of a saint, that is, of a disciple who has lived a life of exemplary fidelity to the Lord. The patron saint provides a model of charity; we are assured of his intercession. The "baptismal name" can also express a Christian mystery or Christian virtue.

"Parents, sponsors, and the pastor are to see that a name is not given which is foreign to Christian sentiment." Canon 855

Hope this helps,

Mike